Martyn Lloyd-Jones
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.

For Christ did not send me to baptize but to preach the gospel, and not with words of eloquent wisdom, lest the cross of Christ be emptied of its power.
1 Corinthians 1:17