As did our Lord, so must we all be welcoming and welcomed. But we are not simply the sum of our sins. When our Lord (and therefore the Church) welcomes us, the welcome does not and cannot include our sin.
I am not my sin. I am a child of God who sometimes falls into sin, and God has provided a remedy for that through the death and resurrection of His Divine Son.
In His love, God provides the medicine we need, but we need to take that medicine of repentance, confession, absolution, and amendment of life, so that we can enter into the Lord's merciful embrace and find the welcome which is waiting for us.
Mercy is not cheap. Christ paid for it with His sacrifice. Some of the Synod Fathers want to offer a "bargain basement" deal -- cheap grace, cheap mercy, cheap faith -- and all it accomplishes it to cheat God's children.