Religions commonly have a practice of making offerings to God. Sometimes it's money. sometimes it's an animal. It is assumed that some type of response to God is necessary. It is part of worship. It is in many cases an attempt to gain God's favor. That's why many people define religion as what people do to attract God's favor. People take initiative to get God on their side.
But Jesus was God, taking the initiative to fix a problem people were powerless to solve. So, the question becomes, "since God acted and move to get on our side, how do we respond?"
If the natural response -- to offer something -- is correct, what do we offer? If he has justified us, redeemed us, sanctified us and adopted us, what do we have that even comes close. Only ourselves.