Psalm 51:17 My sacrifice, O God, is a broken spirit; a broken and contrite heart you, God, will not despise.
God is no longer looking for us to sacrifice animals (or anything else) on an altar to appease Him for our sins!
Christ came to be the ultimate sacrifice so none of that was required any more – but we still have to admit to those sins.
When we openly and humbly admit to our sins before God, He is faithful and just to forgive us just as He promised!