In conversion a change is wrought in the sinner. There is a change from darkness to light, from death to life, and from the power of Satan unto God. There is a change of opinion so that he believes what he once rejected; a change of affection so that he loves what he once hated. What explains such a change? Does the sinner convert himself? Does darkness create light? Does death beget life? Does filth produce purity? Then, and not till then, can the sinner convert himself. If God converts the sinner, does He do it as a matter of obligation or of grace? Paul gives grace credit for his conversion. After speaking of himself as a persecutor of the saints, he says, "But by the grace of God I am what I am."
Grace saves us from the love of sin and from a darkened understanding. This may be called internal salvation, and is the work of the Holy Spirit in us. In this work the Holy Spirit opens the soul's blinded eyes to see the truth of the Gospel. Paul said that his gospel was hid to the lost because their minds were blinded (2 Cor. 4: 4). The death of Christ does not benefit the man who lives and dies without faith in it. And every man of us would so live were it not for the light-giving and life-giving work of the Spirit. Spiritual truths are foolishness to the natural man, even though he be a university professor, and none but the Holy Spirit can make a man spiritual.
Conversion is the work of the Holy Spirit, and His work in us is as much of grace as was the work of Christ for us on the cross. Christ wrought for us on the cross to liquidate our sin-debt; the Holy Spirit wrought in us conviction for sin, and faith in the blood of Christ as the one and only remedy for sin.