I am still reading through Calvin's Institutes, and would here like to share a few things (which I have numbered ad-hoc) Calvin writes about the nature of faith.
1) It is true, indeed, that faith has respect to God only; but to this we shoud add, that it acknowledges Jesus Christ whom He hath sent. God would remain far off, concealed from us, were we not irradiated by the brightness of Christ. All that the Father had, He deposited with His only begotten Son, in order that He might manifest Himself in Him, and thus by the communication of blessings express the true image of His glory. (p. 470)
2) Faith consists not in ignorance, but in knowledge — knowledge not of God merely, but of the divine will. (p. 470)
3) ... it is obvious, that even those who are not yet inbued with the first principles [of true Chistian faith], provided they are disposed to obey, are called believers, not properly indeed, but inasmuch as God is pleased in kindness so highly to honor their pious feeling. (p. 473)
4) Wherefore, if faith declines in the least degree from the mark at which it ought to aim, it does not retain its nature, but becomes uncertain credulity and vangue wandering of mins. The same word is the basis on which it rests and is substained. Declining from it, it falls. Take away the word, therefore, and no faith will remain. (p. 473-474)
5) I am aware it seems unaccountable to some how faith is attributed to the reprobate, seeing that it is declared by Paul to be one of the fruits of election; and yet the difficulty is easily solved: for though none are enlightened into faith, and truly feel the efficacy of the Gospel, with the exception of those who are fore-ordained to salvation, yet experience shows that the reprobate are sometimes affected in a way so similar to the elect, that even in their own judgment there is no difference between them. Hence it is not strange, that by the Apostle a taste of heavenly gifts, and by Christ Himself a temperary faith, is ascribed to them. Not that they truly perceive the power of spiritual grace and the sure light of faith; but the Lord, the better to convict them, and leave them without excuse, instills into their minds such a sense of His goodness as can be felt without the Spirit of Adoption. (p. 478)
6) I deny that the reprobate ever advance so far as to penetrate to that secret revelation which Scripture reserves for the elect only. I therefore deny that they either understand His will considered as immutable, or steadily embrace His truth, inasmuch as they rest satisfied with evanescent impression; just as a tree not planted deep enough may take root, but will in process of time wither away, though it may for several years not only put Knowledge of faith forth leaves and flowers, but produce fruit. (p. 470)
7) This is also indicated by Paul when he says, that "whilst we are at home in the body, we are absent from the Lord: (for we walk by faith, not by sight)" (2 Cor. v. 6,7): thus showing that what we understand by faith is yet distant from us and escape our view. Hence we conclude that the knowledge of faith consists more of certainty than discernment. (p. 482)
8) ... the goodness of God is not properly comprehended when security does not follow at its fruit.
... When we say that faith must be certain and secure, we certainly speak not of an assurnace which is never affected by doubt, nor a security which anxiety never assails, we rather maintain that believers have a perpetual struggle with their own distrust. (p. 484)
9) ... The truth is, that unbelief reigns not in the hearts of believers, but only assails them from without; does not wound them moertally with its darts, but annoys them, or, at the utmost, gives them a wound which can be healed. (p. 488)
[John Calvin (1559), Institutes of the Christian Religion, Translated by Henry Beveridge. Grand Rapids, Eerdmans Publishing Co, MI, USA; Numbering my own.]
We can notice a few things which Calvin says in this long chapter of his (Book III, Chapter II). First of all, Calvin states in passage 3 that faith is used in various ways in the Bible, most notably as describing the outward show of faith. People who profess to be believers but are not true believers are nevertheless called believers in the Bible while they still profess the true faith. Therefore, in passage 5, when talking about the reality of apostasy, Calvin mentioned that these people have a semblance of faith "so similar to the elect" and could be thus called faith, although it is not true evangelical or saving faith. Calvin here states that God instills them a sense of His goodness (His excellence - attribute of God), and therefore further convict them and leave them without excuse for rejecting Him. This only make sense within a Covenant of Works framework, which I would hopefully post about sometime in the near future.
Passage 6 states that only the elect of God, the true believers, will understand God's truth and his will properly, whereas reprobates cannot do so. Illumination is by the Holy Spirit alone (1 Cor. 2:6-16) and therefore only true believers will be able to understand God's truth. By this, we are proclaiming a form of Gnosticism, as God's truth is perspicuous. Rather, as what the Apostle Paul wrote, the reason why they cannot understand God's truth is because they perceive it as foolishness (1 Cor. 1:18). Thus, it is a moral and spiritual inability to receive the Truth, not an intellectual disability on their part.
Passages 1 states that faith must come through Jesus Christ alone, while passage 4 states that faith comes through the Word of God, and both concepts are combined in Jn. 1, where it is stated that Jesus is the Word from the beginning. The revealed Word of God is therefore the words of Jesus Christ who show us the way of salvation by faith in Him. Passage 2 shows that faith consists of knowledge, not ignorance, which destroys all Neo-Orthodox and Emerging Church notions of 'a leap of faith'. Finally, passages 7 to 9 deals with the topic of faith and doubt, and states that with believers, doubt is something external of us which we struggle with, and believers thus struggle with their doubt instead of accepting it. Doubt in a believer is therefore different from doubt in an unbeliever. Therefore, what are we to make of some of the Emergent types who celebrate their doubt and call it faith? These people are showing off the fruit of unbelief and if done of their own free will, manifest that they have not been regenerated by the Holy Spirit and thus are not saved.
In conclusion, faith is something which believes have truly while the reprobates have the most seemingly. Such faith comes through knowledge of God's Word through the person of His Son Jesus Christ. Doubt in believers is an external thing which harrasses them and is struggled with, but never in control of them (much less celebrated), unlike the situation with unbelievers.