“[Saving] faith, wherever it exists, is in every case, without exception, the gift of God and the work of the Holy Spirit. Never yet did a man believe in Jesus with the faith here intended, except the Holy Spirit led him to do so. He has wrought all our works in us, and our faith too. Faith is too celestial a grace to spring up in human nature till it is renewed.” (Charles Spurgeon)
For more on this subject, please visit the Systematic Theology page.