This is another engagement of the truth, and faithfulness, and holiness of God, so that we cannot be deceived in this matter. "There is," says God, "forgiveness with me." The soul says, "How, Lord, will I know, how will I come to be assured of it? For, by reason of the perpetual accusations of conscience, and the curse of the law upon the guilt of my sin, I find it a very hard matter for me to believe. Like Gideon, I want to have a token of forgiveness." Why, look, says God, "I will give you a pledge and token of it, which cannot deceive you. When the world of old was overwhelmed with a flood of waters because of their sins, and those who remained, though they had just cause to expect the same judgment would again befall them or their children, because they saw the same cause of it still remained, the thoughts and imaginations of the hearts of men being still evil, and that continually. To secure them against these fears, I told them that I would destroy the earth no more with water; and I gave them a token of my faithfulness therein, by placing my bow in the cloud. And have I failed them? Though the sin and wickedness of the world has been, since that day, unspeakably great, yet mankind are not drowned again, nor ever will be: I will not deceive their expectation from the token I have given them. Wherever, then, there is a word of promise confirmed with a token, never fear a disappointment. But so is this matter. I have declared that there is forgiveness with me; and to give you assurance thereof, I have ordained this ordinance [baptism] to confirm my word, and take away all suspicion of your being deceived. As the world shall be drowned no more, so neither shall they who believe come short of forgiveness.
– John Owen, "The Forgiveness of Sin", pp. 169-170, language updatedThe pledge and token of God's forgiveness for the Christian is baptism. Do not forget your baptism. Remember your baptism and union with Christ. If guilt and shame attack, remember your union with the once dying and now forever living Lord. And if you have been born-again and have not been baptized, what are you waiting for?