Who does the work in Baptism? This is key question in understanding the doctrine. For if the work in Baptism is done by humans then the benefit of baptism comes from the worthiness of the person being baptized.
If the person being baptized is being baptized based on his or her worthiness, then what is baptism? What benefit is baptism?
Now, if the work in baptism is done by God, then a person is made worthy in baptism. Baptism is a way that God reaches into a person's life and brings grace and favor into that person's life.
Baptism clearly belongs to God. He made the promise attached to baptism. He instituted baptism. God does the work in baptism.
This is a comfort because our relationship with God does not depend upon our strength of faith, strength of character or stength of anything in us. And that's a good thing because we're all sinners and we are weak. If our relationship with God depended upon anything from within us, that relationship would soon fail.
Instead, our relationship with God depends upon His strength. Our relationship with God depends entirely upon God. He gives us our faith, He gives us our strength, He gives us our Salvation. This is a comforting thought, in the darkness of our weakness we will always see the light of His strength!