4 Beware, O Christian, beware of pride. For though you are a follower of the saints, ascribe it always wholly to grace; for that there should be any “remnant” in you, the grace of God has brought to pass, not your own deserts. For the Prophet Isaiah again having this remnant in view, had said already, “Except the Lord of Hosts had left us a seed, we should have become as Sodom, and should have been like Gomorrha.” “So then,” says the Apostle, “at this present time also a remnant is saved through the election of grace.
But if by grace,” says he, “then is it no more of works” (that is, “be now no more lifted up upon your own deserts”); “otherwise grace is no more grace.” For if you build on your own work; then is a reward rendered unto you, not grace freely bestowed. But if it be grace, it is gratuitously given. I ask you then, O sinner, “Do you believe in Christ?” You say, “I do believe.” “What do you believe? That all your sins may be forgiven you freely through Him?” Then have you what you have believed.
O grace gratuitously given! And you, righteous man, what do you believe, that you can not keep your righteousness without God? That you are righteous then, impute it wholly to His mercy; but that you are a sinner, ascribe it to your own iniquity. Be your own accuser, and He will be your gracious Deliverer. For every crime, wickedness, or sin comes of our own negligence, and all virtue and holiness come of God's gracious goodness. “Let us turn to the Lord.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)