You can read about what faith is, according to the Holy Scriptures, the Bible, in an article called: “What Is Faith?”
About faith in Jesus Christ, however, the Scriptures say this:
1 I remind you, brethren, the gospel which I preached to you, which you have also received, in which you have also been established,
2 By which also you are saved, if you hold fast the things which I preached to you, unless you believed in vain.
3 For I originally taught you what I also [myself] received, [that is,] that Christ died for our sins, according to the Scriptures,
4 And that he was buried, and that he rose again the third day, according to the Scriptures,
5 And that he appeared to Cephas, then to the twelve;
6 After that He appeared to more than five hundred brethren at one time, most of whom remain until now, but some have fallen asleep;
7 Then I appeared to James, and also to all the apostles;
8 And after them all he appeared to me, as one of the outcasts.
9 For I am the least of the apostles, and am not worthy to be called an apostle, because I persecuted the church of God.
10 But by the grace of God I am what I am, and His grace toward me did not prove vain; but I labored even more than all of them, yet not I, but the grace of God with me.
11 Whether then it was I or they, so we preach and so you believed.
12 But if it is preached of Christ that he rose from the dead, how is it that some of you say there is no resurrection of the dead?
13 If there is no resurrection of the dead, neither has Christ risen;
14 And if Christ is not risen, then our preaching is vain, and your faith is also vain.
15 Moreover we would also be false witnesses against God, because we would testify against God that he raised up Christ, whom he did not raise up, if, [that is,] the dead were not raised up;
16 For if the dead are not raised, neither is Christ raised.
17 But if Christ has not risen, your faith is in vain: you are still in your sins. (1 Corinthians 15:1-17).
So it is in the death and resurrection of Christ that the Christian’s faith is vital to his salvation. And without faith, as God’s word says, it is impossible to please God:
6 But without faith it is impossible to please God; for he who comes to God must believe that he is, and he who seeks him will be rewarded. (Hebrews 11:6).
Also, those who believe in Jesus that He is the Christ or God’s anointed for the kingdom over the whole world also believe that He is God. Here is how the apostle Thomas testified of his faith and what Jesus answered him:
28 Thomas answered him, “My Lord and my God.
29 Jesus said to him, “You have believed, because you have seen me. (John 20:28,29).
For more on who God is, who Scripture says His Son, Jesus Christ, and the Holy Spirit are, see “A Biblical Perspective on the Essence of God, the Deity of Jesus Christ, and the Holy Spirit” at https://bibleinstruct.blogspot.com/2016/05/blog-post_65.html.
It must be said that faith in Jesus Christ is a more expansive concept than it first appears. Scripture says that in faith you should show good behavior:
5 “In all diligence ye shall show forth in your faith virtue, and in virtue prudence,
6 In prudence temperance; in temperance patience; in patience godliness,
7 In piety brotherlove, in brotherly love.
8 If you have these things in you, and have them in abundance, you will not lack success and fruit in the knowledge of our Lord Jesus Christ.
9 But he who does not have this in him is blind, having closed his eyes and forgotten the cleansing of his former sins.
10 Therefore, brethren, be more and more diligent to make your calling and election sure, for if you do so you will never stumble,
11 For thus your free entrance into the eternal kingdom of our Lord and Savior Jesus Christ will be opened to you. (2 Peter 1:5-11),
obedience to the Lord:
14 As obedient children, do not be conformed to the former lusts that were in your ignorance,
15 but according to the example of him who called you, be holy also in all your conduct.
16 For it is written, “Be holy, for I am holy. (1 Peter 1:14-16).
That faith works by love:
5 and we in spirit expect and hope for righteousness from faith.
6 For in Christ Jesus neither circumcision nor uncircumcision has power, but faith that works by love. (Galatians 5:5,6).
That faith consists of works:
18 But someone will say, “You have faith, and I have works”: show me your faith without your works, and I will show you my faith out of my works. (James 2:18).
That faith is tested, tested by the Lord:
12 Beloved, do not be alienated from the fiery temptation that is sent to you for testing, as an adventure strange to you,
13 But as you partake of Christ’s sufferings, rejoice, that you may rejoice and be exalted at the appearing of his glory. (1 Peter 4:12,13).
And that even those who bear witness to their faith but remain disobedient to God are considered by God to be unbelievers; such people cannot inherit the salvation that can only be found in Christ Jesus:
11 He is the stone, which is neglected by you who are built, but has become the head of the corner, and there is no salvation in anyone else, (Acts 4:11)
And through faith in Him:
16 But having learned that a man is not justified by the works of the law, but only by faith in Jesus Christ, we also have believed in Christ Jesus, that we might be justified by faith in Christ, and not by the works of the law; for by the works of the law no flesh is justified. (Gal.2:16).
As an example of God’s relationship to people’s faith, we can look to the account of Israel’s Exodus from Egypt. It begins with God’s own witness to the Israelites that they believed Moses and the Lord. And they feared Him. Here are the Scripture passages about it:
28 And Moses recounted to Aaron all the words of the Lord who had sent him, and all the signs which he had commanded.
29 So Moses went with Aaron, and they gathered together all the elders of the children of Israel,
30 And Aaron recounted all the words which the Lord had spoken to Moses; and he did the signs in the sight of the people,
31 And the people believed; and they heard that the LORD had visited the children of Israel, and seen their affliction, and they bowed down and worshipped. (Exodus 4:28-31),
31 And the Israelites saw the great hand that the Lord had shown over the Egyptians; and the people feared the Lord, and believed the Lord and Moses his servant. Then Moses and the children of Israel sang this song to the Lord and said (Ex.14:31).
But then something happens, and we see numerous examples of unbelief, disobedience, even rebellion by these same people against God and His words. It is hard to imagine that God’s people did not believe in God, who went before them in a pillar of fire and clouds, drowned their pursuing enemies in the sea, gave manna and water in the wilderness, and performed other miracles, signs, and judgments before them. But it was so!
There is no point in listing everything. Here are just some quotes from Scripture that testify to the departure of God’s people from God:
11 And the LORD said to Moses, “How long will this people vex me, and how long will they not believe me in all the signs that I have done among them? (Num.14:11),
31 And in this wilderness, where, as you saw, the Lord your God carried you, as a man carries his son, in all the way in which you went before you came to this place.
32 But even so you did not believe the Lord your God,
33 Who went before you in the way of seeking a place for you to stay, by night in the fire to show you the way by which to go, and by day in the cloud.
34 And the LORD heard your words, and was angry, and swore, saying:
35 None of these men, of this evil generation, will see the good land that I swore to give to your fathers;
36 Only Caleb the son of Jephunneh will see it; to him I will give the land that he passed through, and to his sons, because he obeyed the LORD. (Deuteronomy 1:31-36),
21 The LORD heard, and the fire was kindled with anger, and fire was kindled against Jacob, and wrath was moved against Israel
22 because they had not believed in God and trusted in His salvation. (Psalm 77:21,22),
12 And they believed his words, and sang his praises.
13 They soon forgot his works and did not wait for his permission;
14 And they were carried away with lust in the wilderness, and tempted God in the uninhabited.
15 And he fulfilled their petition, [but] he sent a pestilence upon their souls.
16 And they envied Moses [and] Aaron, the holy man of the Lord, in the camp.
17 The earth opened up, and swallowed up Dathan and covered the hoard of Abiron.
18 And fire was kindled in their huddle, and the flame consumed the wicked.
19 They made a calf at Horeb, and worshipped the statue;
20 And they exchanged their glory for the image of an ox eating grass.
21 They have forgotten God, their Savior, who has done great things in Egypt,
22 Wonderful in the land of Ham, terrible at the Red Sea.
23 And he would have destroyed them if Moses, his chosen, had not stood before him in the rift, to ward off his fury, that he might not destroy [them].
24 And they despised the desired land; they did not believe his word;
25 And they murmured in their tents, they did not obey the voice of the LORD. (Psalm 105:12-25).
Finally, the apostle Paul concludes that the murmuring, sins, and disobedience of the Israelites, whom the Lord swore that they would not enter his rest, were evidence of their unbelief:
14 For we have been made partakers of Christ, if only we keep the life we have begun firmly to the end,
15 As long as it is said, “Now when you hear his voice, do not harden your hearts, as when you murmur.
16 For some of those who heard him murmured, but not all those who came out of Egypt with Moses.
17 Who then did he resent for forty years? Were not they who had sinned, whose bones had fallen in the wilderness?
18 Against whom did He swear that they would not enter into His rest, but against the disobedient?
19 So we see that they could not enter in because of unbelief. (Hebrews 3:14-19).
But the Lord Jesus Christ also speaks of the same disobedience, of iniquity before God, as the gospel testifies, when he announces the judgment of the wicked who thought they were believers and saved in Christ Jesus, on the last day:
19 Every tree that does not bear good fruit is cut down and thrown into the fire.
20 By their fruits ye shall know them.
21 Not everyone who says to me, ‘Lord! Lord!” will enter the kingdom of heaven, but he who does the will of my Father who is in heaven.
22 Many will say to me in that day, ‘Lord, Lord! Lord, didn’t we prophesy in your name? Didn’t we cast out demons in your name, and in your name did we work many miracles?
23 Then I will declare to them, ‘I have never known you. (Matt.7:19-23).
In other words, God’s word speaks of the same symptoms of unbelief in God and His word that we read about above in the account of Israel on the way out of Egypt, from… Christians! And for this simple reason, these people, having the gifts and power of the Holy Spirit (1 Corinthians 13:1-3), but not having faith, as it turns out, were not even born into God’s family, the Lord never knew them. And into salvation, into God’s rest, they did not enter.
So, faith in God, faith in Jesus Christ is not only faith in the gospel truths that Jesus was born of a virgin, did not sin, died on a wooden cross, shed blood for the sins of the whole world, rose again on the third day, and so on. Faith in Jesus Christ also implies obedience to God’s word.
This, by the way, according to Scripture, is what love is all about:
6 But love consists in our acting according to his commandments. This is the commandment which you have heard from the beginning, that you do according to it. (2 John 1:6).
Disobedient people disobey God’s word because of their unbelief in God.
So when we read the gospel words of our Lord Jesus Christ about the Holy Spirit, that He will come and rebuke the world for sin, that they do not believe in Me:
7 But I tell you the truth, it is better for you that I go; for if I do not go, the Comforter will not come to you; but if I go, I will send him to you,
8 And he will come and convict the world of sin and of righteousness and of judgment:
9 about sin, that they do not believe in me;
10 For righteousness, that I am going to my Father, and you will not see me any more;
11 But of judgment, that the prince of this world is condemned. (John 16:7-11),
We must realize that this word does not refer only to those who say of themselves that they are unbelievers, but more to those who bear witness to their faith, in whose life and ministry even great miracles of God are observed. It is such people, instead of showing in their faith good works, the good fruit of their spirit, who show in their unbelief their disobedience to the word of God, and therefore are not the sheep of God’s flock, as the gospel says:
26 But you do not believe, for you are not of my sheep, as I have told you.
27 My sheep hear my voice, and I know them, and they follow me. (John 10:26,27).
How do sheep show faith to their shepherd? They simply follow him. Sheep that do not follow their shepherd are attacked by predators and perish. So, believers in Jesus Christ first obey His words as they are set forth in the Holy Scriptures, which are inspired by God, as we read:
16 All Scripture is given by inspiration of God, and is profitable for teaching, for reproof, for correction, for instruction in righteousness,
17 That the man of God may be perfect, prepared for every good work. (2 Timothy 3:16,17).
Scripture is the whole Bible, including the epistles of Christ’s apostles:
15 Consider also the longsuffering of our Lord as salvation, just as our beloved brother Paul, according to the wisdom given to him, wrote to you,
16 As he also speaks about it in all the epistles, in which there is something unintelligible, which the ignorant and unstable, to their own destruction, turn, as do the other scriptures. (2 Peter 3:15,16),
which are not the word of men, or, as I have heard from unbelieving “believers,” merely the personal opinions of the apostles, but precisely the word of God:
13 Therefore we also continually give thanks to God, that having received from us the word of God which you have heard, you have not received [as] the word of men, but [as] the word of God-which it is in truth-which also works in you who believe. (1 Thess.2:13).
For more on what Holy Scripture is, see “What is Holy Scripture?” at https://bibleinstruct.blogspot.com/2016/06/blog-post_15.html.
A person who disobeys the Scriptures, disobedient to God’s word, no matter what powers and miracles he may manifest, is an unbeliever in God according to Holy Scripture. And he will not inherit salvation in Jesus Christ.
Read more about salvation in Jesus Christ in the article “All About Salvation” at https://bibleinstruct.blogspot.com/2016/06/blog-post.html.
It is people who only call themselves Christians who are transformed into children of God, just as the prophet Daniel writes:
34 and in the time of their affliction they will have some help, and many will join them, but pretendedly. (Dan.11:34).
The apostle Judas also writes about the same thing, almost word for word:
3 Beloved, I was anxious to write to you about our common salvation, so I thought it right to write to you an exhortation to fight for the faith, which was once delivered to the saints.
4 For some men have stolen in, who from time immemorial have been appointed to this condemnation, ungodly, turning the grace of our God into lewdness, and denying the one master of God and our Lord Jesus Christ.
5 I want to remind you who already know this, that the Lord, having delivered the people out of the land of Egypt, then destroyed the unbelievers,
6 And the angels, who did not keep their dignity, but forsook their dwelling, are kept in eternal bondage, under darkness, for the judgment of the great day.
7 As Sodom and Gomorrah and the cities around them, which committed sexual immorality like them, and walked after other flesh, and were put to death by eternal fire, are made an example.
8 So shall it be with these dreamers, who defile the flesh, and deny their rulers, and speak evil of high authorities.
9 Michael the Archangel, when he spoke to the devil, arguing about the body of Moses, did not dare to utter a reproachful judgment, but said: “May the Lord forbid you.”
10 But these speak evil of that which they do not know; but what they know by nature, they corrupt themselves, like senseless animals.
11 Woe to them, because they walk in the way of Cain; they give themselves up to the enticement of wages, like Balaam, and they persist in ruining themselves, like Korah.
12 Such are they that are a temptation to your supper of love, and as they feast with you, they drown themselves without fear. They are the waterless clouds carried by the wind; the autumn trees, barren, twice dead, expelled;
13 The fierce waves of the sea, foaming with their scum; the wandering stars, to whom the darkness of darkness is for ever.
14 Enoch the seventh from Adam also prophesied about them, saying, “Behold, the Lord is coming with the darkness of his holy angels.
15 to execute judgment upon all, and to reprove all the wicked among them in all the works which their wickedness has produced, and in all the cruel words which the wicked sinners have uttered against him.”
16 They are murmurers, not satisfied with anything, acting according to their lusts (ungodly and lawless); their mouths utter puffed-up words; they exert hypocrisy for self-interest.
17 But you, beloved, remember what the apostles of our Lord Jesus Christ predicted.
18 They told you that in the last time there would be scolders who act according to their own ungodly lusts.
19 These are men who separate themselves (from the unity of the faith), soulless, having no spirit. (Jude 1:3-19).
May God bless and have mercy on you!