2 Thessalonians 2:5 - Albert Barnes' Notes on the Bible

Remember ye not, that, when I was yet with you, I told you these things? - The whole subject of the second coming of the Saviour seems to have constituted an important part of the instructions of Paul when at Thessalonica. He now refers them to what he had told them respecting the great apostasy, to show that his views had not changed, and that he did not mean to have them understand that the world would soon come to an end. He had stated these things to them implying that a considerable interval must elapse before the Saviour would appear. Much of the obscurity of this prophecy arises from the fact, that the apostle alludes to things which he had told them when with them, of which we have now no knowledge. Hence, what would be perfectly clear to them, on reading this letter, is now difficult to be understood.