Institutes Book 3, Chapter 2, Section 11. 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;
284 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 temporary 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.
It is interesting Calvin has to differentiate the faith of some as being so similar to the believer but not essentially the same. There is no real barometer for determining that difference though since even their judgements appear to be the same. How do you know you have real assurance and not merely something almost similar for which God will hold you to greater account?
You are correct, he does say "evanescent".
However, you stopped short.
He goes further to say:
"Should it be objected, that believers have no stronger testimony to assure them of their adoption, I answer, that though there is a great resemblance and affinity between the elect of God and those who are impressed for a time with a fading faith, yet the elect alone have that full assurance which is extolled by Paul, and by which they are enabled to cry, Abba, Father. Therefore, as God regenerates the elect only for ever by incorruptible seed, as the seed of life once sown in their hearts never perishes, so he effectually seals in them the grace of his adoption, that it may be sure and steadfast. But in this there is nothing to prevent an inferior operation of the Spirit from taking its course in the reprobate. Meanwhile, believers are taught to examine themselves carefully and humbly, lest carnal security creep in and take the place of assurance of faith. We may add, that the reprobate never have any other than a confused sense of grace, laying hold of the shadow rather than the substance, because the Spirit properly seals the forgiveness of sins in the elect only, applying it by special faith to their use. Still it is correctly said, that the reprobate believe God to be propitious to them, inasmuch as they accept the gift of reconciliation, though confusedly and without due discernment; not that they are partakers of the same faith or regeneration with the children of God; but because, under a covering of hypocrisy, they seem to have a principle of faith in common with them. Nor do I even deny that God illumines their minds to this extent, that they recognize his grace; but that conviction he distinguishes from the peculiar testimony which he gives to his elect in this respect, that the reprobate never attain to the full result or to fruition. When he shows himself propitious to them, it is not as if he had truly rescued them from death, and taken them under his protection. He only gives them a manifestation of his present mercy. In the elect alone he implants the living root of faith, so that they persevere even to the end. Thus we dispose of the objection, that if God truly displays his grace, it must endure for ever. There is nothing inconsistent in this with the fact of his enlightening some with a present sense of grace, which afterwards proves evanescent."
-John Calvin, Institutes of the Christian Religion, Book III, Chapter 2, Section 11
Everything he wrote here goes right along with what is taught in scripture.
cf Mt. 13:3-23, 24-30, 31-32, 33; Mk. 4:1-25; Lk. 8:4-15
There will be quite a few who seem, appear to have the faith, have the works, have what looks like Christianity, but in reality, are about as far from God as one can get. They appear to have faith but not long afterwards it becomes "evanescent" ( tending to vanish like vapor;
Merriam-Webster)
And why does their faith disappear?
"Although faith is a knowledge of the divine favor towards us, and a full persuasion of its truth, it is not strange that the sense of the divine love, which though akin to faith differs much from it, vanishes in those who are temporarily impressed. The will of God is, I confess, immutable, and his truth is always consistent with itself; but 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 an 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 forth leaves and flowers, but produce fruit. In short, as by the revolt of the first man, the image of God could be effaced from his mind and soul, so there is nothing strange in His shedding some rays of grace on the reprobate, and afterwards allowing these to be extinguished. There is nothing to prevent His giving some a slight knowledge of his Gospel, and imbuing others thoroughly. Meanwhile, we must remember that however feeble and slender the faith of the elect may be, yet as the Spirit of God is to them a sure earnest and seal of their adoption, the impression once engraven can never be effaced from their hearts, whereas the light which glimmers in the reprobate is afterwards quenched."
Ibid, Section XII
Just like scripture:
"They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us." -1 Jn. 2:19 (KJV)
In many ways, James says the same thing:
"For the sun is no sooner risen with a burning heat, but it withereth the grass, and the flower thereof falleth, and the grace of the fashion of it perisheth: so also shall the rich man fade away in his ways." -Jas. 1:11 (KJV)
Seems an awful lot like the same thing said here:
"And when the sun was up, they were scorched; and because they had no root, they withered away." Mt. 13:6 (KJV)
So I see no conflict.
God Bless
TIll all are one.
