Yeah, but Christ always WAS God and didn't need God's forgiveness. You see how crazy this sounds?
You might want to go back and think through your theology.
God the Son, identifiable as Jesus Christ, was also human by the Incarnation.
God the Father JUDGED all sins of humanity, past, present, and future, when they were imputed to Jesus Christ at the Cross.
Note: the Cross was all JUDGMENT, not FORGIVENESS.
The penalty of sin is death, which is a state of existence involving separation.
When the soul of Jesus Christ was judged of those imputed sins, He then suffered an immediate SPIRITUAL DEATH,...a separation from God the Father. This is manifest by His testimony on the Cross, recorded in Matthew 27:46
(46) And about the ninth hour Jesus cried with a loud voice, saying, Eli, Eli, lama sabachthani? that is to say, My God, my God, why hast thou forsaken me?
The human anthropology is composed of body, soul, and spirit.(Heb 4:12; James 2:26; 1Thes 5:23)
We know Jesus Christ physically died by the Roman soldier who pierced His side and out poured blood and water, indicating the plasma had already begun to separate.
His body went to the grave, His Spirit was returned to the Father, and His Soul descended to Sheol.
Three days later His Body was Resurrected from the grave, His Soul ascended from Hades, and His Spirit returned from God to His body and soul, becoming born again in a resurrected body.
Had He not died spiritually, we would not have a sacrificial atonement to satiate the integrity of God the Father’s Perfect Holiness, which is comprised of His Perfect Righteousness and His Perfect Justice (manifest by the 2 cherubim on the Mercy Seat in His Tabernacle).
The Gospel message, the good news, is that He did pay that price, and now HAS been FORGIVEN off all humanities’ sins which had been imputed upon Him, because He is Resurrected, even now ascended to the right hand of God the Father in Heaven.
We are still born from the bloodline of Adam and original sin, so are already condemned, until we come to have faith in Christ at the Cross. Because of that event, God the Father is now free to remain true to His integrity, His Essence, when He recognizes that faith and in response, now that the payment for sin has been made, is free to give us a regenerated human spirit, a second birth of a new man in us.
In God’s Plan, Jesus Christ, in His humanity died for us on the Cross, so that whosoever believes on Him, might have eternal life. God the Son needed the Forgiveness of God the Father, once the payment of sin had been made, to then be resurrected.
While God the Father, Son, and Holy Spirit are one, He reveals Himself to us in three persons. This also assists us in understanding our role to God when we follow the path of Jesus Christ.