8 But even if we [no matter who it is], or an angel from heaven [supposed].
Yeah, like what person is going to say, "I just had a demonic hellbound angelic visit" None! Deceivers always claim it came by "an angel from heaven." Like saying that gives this angelic visit any merit!!!
preach [evangelize] any other gospel to you than what we have preached to you,
We won't overly expound this verse, but to point out that Paul again emphasizes the curse coming to those teaching a False Gospel.