Why then does the Holy Spirit call baptism the water of rebirth and the washing away of sins [if water doesn't save]?

God has good reason for these words. To begin with, God wants to teach us that the blood and Spirit of Christ take away our sins just as water removes dirt from the body.¹ But more important, God wants to assure us, by this divine pledge and sign, that we are as truly washed of our sins spiritually as our bodies are washed with water physically.²