John Calvin on 2 Thessalonians 2:5

5 Do ye not remember? This added no small weight to the doctrine, that they had previously heard it from the mouth of Paul, that they might not think that it had been contrived by him at the instant. And as he had given them early warning as to the reign of Antichrist, and the devastation that was coming upon the Church, when no question had as yet been raised as to such things, he saw beyond all doubt that the doctrine was specially useful to be known. And, unquestionably, it is really so. Those whom he addressed were destined to see many things that would trouble them; and when posterity would see a large proportion of those who had made profession of the faith of Christ revolt from piety, maddened, as it were, by a gad-fly, or rather by a fury, “Se reuolter de la vraye religion, et se precipiter en ruine comme gens forcenez, ou plustost endiablez;” — “Revolt from the true religion, and plunge themselves in ruin like persons enraged, or rather possessed.” what could they do but waver? This, however, was as a brazen Murus aheneus. See Hor. Ep. 1:1, 60. wall “Mais voici en cest endroit qui leur deuoit seruir d’vne forteresse inuincible;” — “But behold in this matter what would furnish them with an invincible fortress.” — that matters were so appointed by God, because the ingratitude of men “L’ingratitude execrable et vileine des hommes;” — “The execrable and base ingratitude of men.” was worthy of such vengeance. Here we may see how forgetful men are in matters affecting their everlasting salvation. We must also observe Paul’s mildness; for while he might have been vehemently incensed, “Contre les Thessaloniciens;” — “Against the Thessalonians.” he does but mildly reprove them; for it is a fatherly way of reproving them to say to them, that they had allowed forgetfulness of a matter so important and so useful to steal in upon their minds.