When Jesus died on the cross, in essence, God wrote the check of salvation and offered it to all men. To receive the benefit of this gift, we must turn over the check, write our name on the back, take it to the bank, and cash it. In the same way we must believe, confess, repent, and be baptized in order to enter into the body of Christ and receive the gift of salvation. This does not mean we have earned our salvation, it just means we have received God's gift of grace on His terms.
