Jamieson, Fausset and Brown on 1 Thessalonians 3:13

13. your hearts--which are naturally the spring and seat of unholiness.

before God, even our Father--rather, "before Him who is at once God and our Father." Before not merely men, but Him who will not be deceived by the mere show of holiness, that is, may your holiness be such as will stand His searching scrutiny.

coming--Greek, "presence," or "arrival."

with all his saints--including both the holy angels and the holy elect of men (1Th 4:14; Da 7:10; Zec 14:5; Mt 25:31; 2Th 1:7). The saints are "His" (Ac 9:13). We must have "holiness" if we are to be numbered with His holy ones or "saints." On "unblameable," compare Re 14:5. This verse (compare 1Th 3:12) shows that "love" is the spring of true "holiness" (Mt 5:44-48; Ro 13:10; Col 3:14). God is He who really "stablishes"; Timothy and other ministers are but instruments (1Th 3:2) in "stablishing."