From Luther’s Small Catechism:
“What does such baptizing with water indicate?”
“It indicated that the Old Adam in us should by daily contrition and repentance be drowned and die with all sins and evil desires, and that a new man should daily emerge and arise to live before God in righteousness and purity forever.”
Baptism the one-time act, which renews through faith, indicates that new renewal through faith must occur for every day of life. This is not to be an erratically-changing shapeshifter, as though we burned through grace like gasoline, but a steady repetition of hundreds of thousands of patient resurrections–untiring repentenaces and contritions until all living memory is of Christ and His cross. Wisdom is always attained by this slow plodding. If God can supply true washing from sin in simple water-immersion, then we can trust Him to supply “righteousness and purity forever” through daily renewed faith. He will turn our time into eternity.