Martyn Lloyd-Jones
No man can believe the gospel in and of himself; the power of the Spirit alone can lead anyone to belief; without it we are spiritually dead and lost and ruined and under the wrath of God.

Why is it that some have believed? It is because the Spirit has sanctified them, has set them apart, has called them out. It is the work of the Spirit in conviction, and calling out, and giving power to believe.
Martyn Lloyd-Jones