What is baptism? Martin Luther in his Small Catechism for fathers to teach their children says: Baptism is not just plain water, but it water used by God’s command and connected with God’s Word. The reminders of your baptism may be a certificate, messages from your parents or people who were present at your baptism. Or if baptized when older than your own memories of your baptism. I have the baptismal certificate that gives the date for my baptism. I have the testimony of the pastor who performed that baptism that I cried.