2 Timothy 1:9

Who has saved us and called us with a holy calling, not according to our works, but according to His own purpose and grace which was given to us in Christ Jesus before time began. who has saved us. Then also concerning the cooperation of …

When Paul says that we are not called according to our works, he means that all who are called are sinners, though by comparison with others some were found to be more worthy. With regard to God's own grace, however, all were totally unworthy.

Why, then, is it that, in what follows, where they mention what they themselves think, they say they confess "That grace also assists the good purpose of every one, but that yet it does not infuse the desire of virtue into a reluctant heart"? Because they so say this as if man of himself, without God's assistance, has a good purpose and a desire of virtue; and this precedent merit is worthy of being assisted by the subsequent grace of God. For they think, perchance, that the apostle thus said, "For we know that He worketh all things for good to them that love God, to them who are called according to the purpose," so as to wish the purpose of man to be understood, which purpose, as a good merit, the mercy of the God that calleth might follow; being ignorant that it is said, "Who are called according to the purpose," so that there may be understood the purpose of God, not man, whereby those whom He foreknew and predestinated as conformed to the image of His Son, He elected before the foundation of the world. For not all the called are called according to purpose, since "many are called, few are chosen." They, therefore, are called according to the purpose, who were elected before the foundation of the world. […]

"According to the power of God; Who hath saved us, and called us with a holy calling, not according to our works, but according to His own purpose and grace, which was given us in Christ Jesus before the world began." More especially because it was a hard thing to say, "Be partakers of afflictions," he again consoles him. Reckon that thou sustainest these things, not by thine own power, but by the power of God. For it is thy part to choose and to be zealous, but God's to alleviate sufferings and bid them cease. He then shows him the proofs of His power. Consider how thou wast saved, how thou wast called. As he elsewhere says, "According to His power that worketh in us." (Eph. iii. 20) So much was it a greater exercise of power to persuade the world to believe, than to make the Heavens. But how was he "called with a holy calling"? This means, He made them saints, who were sinners and enemies. "And this not of ourselves, it was the gift of God." If then He is mighty in calling us, and good, in that He hath done it of grace and not of debt, we ought not to fear. For He Who, when we should have perished, saved us, though enemies, by grace, will He not much more cooperate with us, when He sees us working? "Not according to our own works," he says, "but according to his own purpose and grace," that is, no one compelling, no one counseling Him, but of His own purpose, from the impulse of His own goodness, He saved us; for this is the meaning of "according to His own purpose." "Which was given us before the world began." That is, it was determined without beginning that these things should be done in Christ Jesus. This is no light consideration, that from the first He willed it. It was not an after-thought. How then is not the Son eternal? for He also willed it from the beginning.

He presents proofs of the power of God. He saved us, he says, and called the estranged to Himself, in order to make us holy. So, He Who saved us when we were unwilling, will all the more help us now that we are willing. …