If Jesus were not fully God then his sacrifice would be useless. Only a being that is fully God and fully Man would be able to provide atonement for all, who come to him. Animal Sacrifice was only good for a year.
The Early Church Fathers were taught by the Apostles.
Ignatius (AD 50-117)
"Being as you are imitators of God, once you took on new life through the blood of God you completed perfectly the task so natural to you."
For our God, Jesus the Christ, was conceived by Mary according to God’s plan, both from the seed of David and of the Holy Spirit.
when God appeared in human form to bring the newness of eternal life.
The Letter of Polycarp to the Philippians, he mentions "the God and Father of our Lord Jesus Christ" and "our Lord and God Jesus Christ."[4]
Now may the God and Father of our Lord Jesus Christ, and the eternal High Priest himself, the Son of God Jesus Christ, build you up in faith and truth and in all gentleness and in all freedom from anger and forbearance and steadfastness and patient endurance and purity, and may he give to you a share and a place among his saints, and to us with you, and to all those under heaven who will yet believe in our Lord and God Jesus Christ and in his Father who raised him from the dead.
https://www.bethinking.org/jesus/the-early-church-fathers-on-jesus