Paul has been quoted, “It is by GRACE you are saved.”e.g., not your work.Presenting the message of the gospel and getting back a response of faith in the death and resurrection of the Lord Jesus Christ is a great act of spiritual warfare. Ground is taken from the enemy. The receptive act of faith in believing the gospel has justified God to forgive sin in the new believer based on the death of Christ and gracefully convert them from darkness to light. There is no room for boasting in the one preaching or the one receiving salvation. It is all by God's grace.
13 Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son: