Albert Barnes Commentary James 1:16

"Be not deceived, my beloved brethren." — James 1:16 (ASV)

Do not err, my beloved brethren. This is said as if there were great danger of error in the point under consideration. The point on which he would guard them seems to have been regarding the opinion that God was the author of sin, and that the evils in the world are to be traced to him. There was great danger that they would embrace that opinion, for experience has shown that it is a danger into which men are always prone to fall. Some of the sources of this danger have been alluded to already (see Barnes on James 1:13).

To meet the danger, he says that, so far is it from being true that God is the source of evil, that he is in fact the author of all that is good: every good gift and every perfect gift (James 1:17), is from him (James 1:18).