Galatians 1:6,7

Unto another gospel: which is not another. — It is to be regretted that the English language hardly admits the fine shade of distinction which exists here in the Greek. The Greek has two words for “another:” one (the first of those which is here used) implying a difference in kind, the other implying mere numerical addition.

Another gospel do I call it? That would seem to concede its right to be called a gospel at all. It might be supposed to be some alternative theory, existing side by side with that which you originally heard; but this cannot be. This “other gospel” is not a second gospel; for there cannot be two gospels. The inference, therefore, to be drawn is that it is not a gospel in any sense of the word. This, then, may be dismissed. It is no true gospel, but only mischievous and factious meddling on the part of certain false teachers.