5 to whom be glory forever and ever. Amen. -Galatians 1:5 BSB
The phrase “to whom be glory forever and ever” refers to the Godhead in verses 3 & 4—God the Father and the Lord Jesus Christ. The reason that God the Father and the Lord Jesus Christ deserve all the glory is because of His sacrificial display of love for all the sinners. It was demonstrated by Jesus’ death and resurrection, who died on our behalf to give us a chance to get saved and escape the torments of Hell.
The word “Amen” in verse 5, when used at the end of a sentence, means “so let it be.” Strong’s Gr.#281