en_tn_lite_do_not_use/gal/01/06.md

I am amazed

"I am surprised" or "I am shocked." Paul was disappointed that they were doing this.

you are turning away so quickly from him

Here "turning away ... from him" means to doubt or stop trusting God. Alternate translation: "you are so quickly doubting him"

him who called you

"God, who called you." This means God has appointed or chosen people to be his children, to serve him, and to proclaim his message of salvation through Jesus.

by the grace of Christ

"because of Christ's grace" or "because of Christ's gracious sacrifice"

you are turning to a different gospel

Here "turning to" means to start to believe something. Alternate translation: "you are instead starting to believe a different gospel"