Adam Clarke on James 1:22

But be ye doers of the word - They had heard this doctrine; they had believed it; but they had put it to no practical use. They were downright Antinomians, who put a sort of stupid, inactive faith in the place of all moral righteousness. This is sufficiently evident from the second chapter.

Deceiving your own selves - Παραλογιζομενοι ἑαυτους· Imposing on your own selves by sophistical arguments; this is the meaning of the words. They had reasoned themselves into a state of carnal security, and the object of St. James is, to awake them out of their sleep.