What is it? Biblically speaking, it is both a verb and a noun.
Ok, ok… so there are 2 types of nouns.
First, if one speaks of “the Christian faith,” then they are remarking on beliefs that belong solely to Christians. Belief in Christ as the Son of God (meaning also the Savior) is the Christian faith. It was Christ that overcame the fallen world and its fallen “prince” (John 16:33; Eph. 2:2), and it was Christ that provided for those who receive him to be titled born-again “children of God” (John 1:12, 13). Therfore, it is only the children of God that overcome the fallen world, because the Christian faith is the only faith that overcomes the [fallen] world (1 John 5:4). No other faith provides a remedy for the fallen world and its fallen prince, much less acknowledges them accurately.
Second, if someone says, “I have all faith that…,” then he or she is expressing within them resides an assurance, a belief. That person is telling you that even though a thing may not be seen or tangible yet, there is something lodged in their soul that provides them with evidence enough to foster their expectations–their hope. (Heb. 11:1) And, this is not unreasonable; there is much to life which is unseen and untouched.
How does biblical faith get lodged in one’s soul? Very simply, the Bible does it (Rom. 10:17) when one lets it (Heb. 4:2). And the key to letting it produce faith is realizing whose word it is (Rom. 3:2, 1 Thess. 2:13). The Bible is God’s Word, or his collective words to mankind. When someone reads God’s words, whether they are promises or truths or maxims or perspectives on history and revelations of future prophecies, it is exactly like a seed is planted and watered in the reasoning and feelings and will of that person (1 Pet. 1:23). It is a miracle of sorts. In that way, faith is a gift just as grace is a gift (Eph. 2:8,9). The more one reads the Word and studies it and tests it, the more he sees it is true and supernatural. So, assurance starts to grow, if one will let it. But, it cannot sprout until the seed of truth is planted. That is why Christ emphasized that his disciples should teach and baptize as they go (Matt. 28:19,20).
Just like you have the choice to believe anyone else’s words, you have the choice to believe (trust) God’s words. That being said, God does not expect you to trust him without knowing what he presents is Truth or that He is Himself trustworthy. Little by little, one line at a time upon another line, here a little and there a little, God does things, sometimes indescribable things, to give us assurances of his trustworthiness or of his care or of his fairness… and some things, like creation, are self-evident. Look for these “tokens for good” (Ps. 86:17). At the same time, and though paradoxical it is all about your willingness to read the Word and entertain it and agree with it and trust it and act upon it (Phil. 2:13). Thankfully, “God is not like a man, in that, he should lie…” (Numbers 23:19) When one lets faith grow in his heart, that is when it starts to become an action word.
Faith can be exercised only in the middle of challenges to it, or in the face of what seemingly contradicts it. There are many paradoxes which muddle things up to our “own understanding,” but in the end, we see they were paradoxes and nothing more. Hardship, time spent waiting, suffering and persecution, fears and doubts, enduring loss, perplexing circumstances, broken love, strong desires and the deceptive nature of sin, half-truths or even out-and-out lies all wage war on someone’s belief. God knows this, and he isn’t angry or even disapointed in you for it (Matt. 11:1-15). Rather, he invites you to come to his Throne of Grace and talk plainly and openly about how you feel and what you think, just like King David and Job complained to God (Heb. 4:16). If you’ll ask him, he abundantly will give you what you need to see or know, so that you can believe what you should (Mark 9:24). Now, that supply may come in the form of his wisdom (which is different from ours — James 1:5), or it may come after many years (Heb. 6:11-20), or it may come in the form of relationships with others who have gone through similar things and have been helped or taught by God themselves (2 Cor. 1:4ff). Whatever the case, his supply for your faith will come as a result of your praying it through, as a way to submit yourself to God and resist the enemy (Matt. 6; James 4:7) and as a result of remembering his words (Ps. 119:49-56).
There are 3 elements involved in describing the human side (responsibility) of this matter of faith:
Receive: (1 Thess. 1:5,6, John 1:12) — When one receives the Bible or a specific truth from the Bible as God’s word, then that is a reception and faith is exercised. Furthermore, this reception (when concerning the Gospel) is of a Person, Jesus Christ. But, any part of the Bible can be received as truth and does not necessarily mean that one has received Jesus as the Son of God, the Savior of all. Receiving is a “taking for one’s self.” Think: “I am hungry and I need it.” In other words, when you see the “food” of God’s word (Dt. 8:3; Matt. 4:4) you say, “this is good, this is for me and I take it; it is necessary for life.” That’s faith. That’s receiving. And, again, it can be Jesus that you take to yourself as the Bread of Life (John 6:35), but it also can be any part of God’s word leading up to faith in Christ since.
Accept: (1 Thess. 2:13) — Think about having guests over for dinner. If one uses an elegant term, then she might say she “entertains” them. One might take them out to the back deck and mix and mingle and provide space for the one received. In the same way, one can receive the words of God as truth but that is not the same as accepting. When one receives the words of God as God’s, he or she has “taken them” based on need and the elemental realization that it is powerful enough to meet a need. But when one accepts the words of God, especially about Jesus, then that one has “entertained” the Truth in his or her mind and emotions; and the truth has found a welcome place there. Yes, it is welcomed, it is enjoyed and known better; it is admired in all of its aspect. One could say that accepting is like taking but with a good bit of understanding (from illumination) added due to one’s willingness to know a thing (or, a person–Jesus) better. One has made space in their mind and life for the Truth, and God has filled it with a fuller understanding.
Believe: (1 Thess. 2:13; John 1:12; Acts 16:31; Rom. 10:8-11 ) — This term has to do with the human will, whereas receiving and accepting have to do with the mind and emotions. If one has received and accepted the Truth, especially about Jesus Christ, then “believe” is always to be the following thing. The Bible always indicates believing as coming after either accepting or receiving, and it indicates believing as the essential factor in one’s being secured in a heavenly eternal destiny (John 3:18; 1 John 5:10; Mark 16:16), and it is a matter of the individual will of one who has already received the Word and even accepted it. In other words, one can realize the necessity of the Truth in God’s Word and one can also have received illumination to that Truth for their understanding, but that same person might choose not to depend on Jesus for reconciliation to God and regeneration of his nature (Heb. 4:2). But, when one does believe, it is both due to an assurance within you (from receiving and accepting) and results in an assurance that the Holy Spirit gives. [please see In Defense of the Spirit for an explanation of that assurance] Furthermore, when one believes, there are results in the life, because the Truth has been woven into the warp and woof or the fibers of one’s being as the result of the Spirit’s work. For example, the Thessalonians told everyone about Christ (imitating Paul’s missionary team) and kept believing despite hardships (1 Thess. 1 & 2). They lived by (or, “out of” according to) their faith (Hab. 2:4, Rom. 1:17, Gal. 2:20, 3:11, Heb. 10:38) in Jesus’ being the Son of God, and that is an evidence to their fellow man of their faith as something alive and not just an idea (James 1 & 2) and leads to yet more and more understanding (Philemon v.6).
For illustration, let’s use medicine and a doctor. After all, Jesus said that he is a Physician sent to heal the sick. So, God is aware of your illness (sin) even though you aren’t. Accordingly, God makes the provision for your need in Jesus. You hear from God that you are sick (through the Bible or through someone who tells you the Bible’s words). You review the reasonability of his examination, which proves by your own symptoms (actions and thoughts/desires) that your nature is indeed fundamentally flawed compared to God’s. Therefore, You “take” (accept) the prescription of Jesus for your own need. But, you drive home with the prescription in your car, thinking about it all the way and grow increasingly convinced that since the Doctor knew your condition so well, he also has prescribed the correct remedy (“receive“). You arrive home and put the prescription in your cabinet. Before bed, you have the choice of your own will to take the prescription; and of course, if one does not see a need for Jesus or trust the word of the Doctor, then one chooses not take Him. If one does see his need for Jesus in light of his own sins, then he repents (changes his mind about himself and his own ways) toward God while believing (depending, actively trusting) Jesus is the Lamb who takes away the sins of the world. You take the pill, and you are made better. What is more, because you have been made better through the power of the remedy via your actively trusting it (swallowing it), then you start to feel new life and restoration in you. You enjoy that newness and live in it, counting on (going off of the reality, believing) the fact that you were made whole. So, things change. It would be very sad indeed for someone to have been healed physically, but who refused to believe it. Their being whole would do them no good… no change. Even so, when a believer does not go through life by counting on his having been healed and made whole from sin (as a matter of fact), then he does not experience that newness of life (Rom. 6:1-23; 8:1-18; Gal. 2:20).
By the way, “without faith, it is impossible to please God” (Heb. 11:6); that is why living by faith (“out of” faith) is necessary for a believer (Heb. 10:38). God just wants your trust, and really he is the only one who deserves it… that is why you can’t please him without trusting him. But, if you do trust him (especially concerning Christ), then God will credit you with righteousness just like he did Abraham, the “father of faith” (Rom. 4). If you don’t trust him yet, check out what he says in his Word. It is only there that your faith will grow and change most everything about the way you see existence and your purpose in it. God has a whole bag full of things for which he wants you to believe him. Faith in Christ for eternal pardon is just the beginning.