If we believe not, yet he abideth faithful - This cannot mean that, if we live in sin, he will certainly save us, as if he had made any promise to the elect, or formed any purpose that he would save them; whatever might be their conduct; because:
(1) He had just said that if we deny him he will deny us; and,
(2) There is no such promise in the Bible, and no such purpose has been formed. The promise is, that be that is a believer shall be saved, and there is no purpose to save any but such as lead holy lives. The meaning must be, that if we are unbelieving and unfaithful, Christ will remain true to his word, and we cannot hope to be saved. The object of the apostle evidently is, to excite Timothy to fidelity in the performance of duty, and to encourage him to bear trials, by the assurance that we cannot hope to escape if we are not faithful to the cause of the Saviour. This interpretation accords with the design which he had in view.
He cannot deny himself - Implying that it would be a denial of his very nature to save those who are unfaithful. He is holy; and how can he save one who is unholy? His very nature is purity; and how can he save one who has no purity? Let no one, then, suppose that, because he is elected, he is safe, if he lives in sin. The electing purpose of God, indeed, makes salvation sure; but it is only for those who lead righteous lives. Nothing would be mere dishonorable for God than to resolve to save a man that lived habitually in sin; and if that were the doctrine of election, it would deserve all the opprobrium that has ever been heaped upon it.