18. ἀλλʼ ἐρεῖ τις. The objector denoted by τις is virtually St James. The ἀλλά is adversative to Jam 2:15-16. Shew me the faith without works, i.e. Shew me a faith which is consistent with standing aloof and bidding the hungry begone and feed himself and the naked clothe himself. Such faith is indeed a thing inconceivable. But I will shew you my faith as evidenced and proved by works of ἔλεος.
ἐκ τῶν ἔργων, as an inference or deduction from its works.