There are many reasons why Jesus came to the Earth.
However, all reasons and thoughts about His purpose can be boiled down to one thing.
Unity through love.
In order to reconcile sinners with God, there had to be one to unify each party.
We don't need a priest, for Christ is our priest.
We don't need a sacrifice, for Jesus is our sacrifice.
We don't need suffer, because He suffered.
Jesus prays for us.
"I pray for those who believe in Me...May they also be one in Us, so the world may believe You sent me." John 17
We are made one with the Father because of Christ. As believers we are united together with each other and with God.