1 Thessalonians 2:3

γάρ : Our mission (whatever that of others may be) is not the outcome of self-seeking, otherwise it would readily be checked by such untoward circumstances. Our confidence is in God, not in ourselves; our work is not self-appointed but a sacred trust or commission, for which we are responsible to Him (4). Hence, discouragement and hesitation are impossible. Paul argues that the very fact of their cheerful perseverance at Thessalonica, after their bad treatment at Philippi, points to the divine source and strength of their mission; what impelled them was simply a sense of lasting responsibility to God, upon the one hand, and an overpowering devotion to men upon the other (cf. the διʼ ὑμᾶς of 1 Thessalonians 1:5), for the gospel's sake. Had the apostles yielded to feelings of irritation and despondency, giving up their task in Macedonia, after the troubles at Philippi, or had they conducted themselves at Thessalonica in such a way as to secure ease and profit; in either case, they would have proved their mission to be ambitious or selfish, and therefore undivine. As it was, their courage and sincerity were at once the evidence and the outcome of their divine commission. πλάνης, “error” (cf. Armitage Robinson on Ephesians 4:14). Their preaching did not spring from some delusion or mistake. Paul was neither fool nor knave, neither deceived nor a deceiver (δόλῳ). Nor was his mission a sordid attempt (ἀκαθαρσίας) to make a good thing out of preaching, the impure motive being either to secure money (cf. πλεονεξίας 1 Thessalonians 2:5, and 1 Thessalonians 2:9), or to gain a position of importance (1 Thessalonians 2:6) and popularity. Cf. Tacit., Annal., vi, 21 (of Tiberius' attitude to astrologers) “si uanitatis aut fraudum suspicio incesserat”. Both features were only too familiar in the contemporary conduct of wandering sophists, ἀρεταλόγοι, and thaumaturgists (e.g., Acts 13:10, and Clemen's article in Neue Kirchl. Zeitschrift, 1896, 151 f.) whose practices would also explain the literal interpretation of ἀκ. (= sensuality). But the context favours the associations of greed (cf. Ephesians 5:3), as in the case of πλεονεξία. On the persuasiveness of sincerity in a speaker, i.e., the extent to which his effectiveness depends upon his hearers' conviction of his own earnestness and honesty, see Aristotle's analysis of ἠθικὴ πίστις (Rhet., ii. 1) and Isocrates' description of εὐνοίας δύναμις (Orat., xv. 278, 279).