The Lord Jesus came to do what we cannot do. He came to fulfil the Law: man's moral obligation to God.
He didn't come into the world to replace what the prophets had already done.
The Old testament reveals God's justice towards law breakers and a coming saviour.
In the New Testament Jesus Christ reveals God's love to us by fulfilling what justice demands of us: he is that saviour.
Mathew 5:17
God's purpose in Jesus: "For God sent not his Son into the world to condemn the world; but that the world through him might be saved." John 3:17 (kjv)
