John Gill Commentary James 2:18

"Yea, a man will say, Thou hast faith, and I have works: show me thy faith apart from [thy] works, and I by my works will show thee [my] faith." — James 2:18 (ASV)

Yea, a man may say, you have faith, and I have works That is, a true believer in Christ may very justly call upon a vain boaster of his faith, who has no works, to give proof and evidence of it, and address him after this manner; you say you have faith, be it so that you have; I have works, you see I have, I say nothing about my faith at present; now,

show me your faith without your works, if you can; see what ways, means, and methods you can make use of, to make it appear to me, or any other, that you have the faith you talk of: the words are a sort of sarcasm and jeer upon the man, and yet very just, calling upon him to do that which is impossible to be done, and thereby exposing his vain boast; for faith is an inward principle in the heart; an hidden thing, and cannot be seen and known but by external acts; and where it is right, it is operative, and shows itself by works, which is not practicable in those who have none:

and I will show you my faith by your works; there may be indeed an appearance of good works, where there is no faith, as in the Heathens, in the Scribes and Pharisees, and in the Papists, and others; and on the other hand, there may be the principle of faith implanted, where there is not an opportunity of showing it by a series of good works, or a course of godly living, as in elect infants dying in infancy, and in those who are converted in their last moments, as the thief upon the cross; wherefore works are not infallible proofs and evidences of faith, yet they are the best we are capable of giving of it to men, or they of receiving.

In short, works may deceive, and do not infallibly prove truth of faith, yet it is certain, that where they are not, but persons live in a continued course of sinning, there cannot be true faith.