If I really want to go to heaven, I must change the way I think, and thus, change the way I live. That might call for me to change my belief system and/or my behavior.
If I really want to go to heaven, I must say what God says about Jesus and live my life accordingly.
If I really want to go to heaven, I must be immersed in water the way God specifies; i.e. for the purpose of being cleansed from my sins by the blood of Jesus Christ.