Thematic Bible: Pervert the gospel of Christ

I am astonished that you people are so quickly abandoning God [i.e., by rejecting His truth], who called you [to Himself] through the unearned favor bestowed [on us] by Christ. [You are turning] to a different "gospel," although it is really not a different one, but rather some people are causing you trouble by trying to pervert the [true] Gospel of Christ.