Never mind the epistles. Let’s see what Jesus Christ had to say about this: Mark 9:38-40 (KJV) 38And John answered him, saying, Master, we saw one casting out devils in thy name, and he followeth not us: and we forbad him, because he followeth not us. 39But Jesus said, Forbid him not: for there is no man which shall do a miracle in my name, that can lightly speak evil of me. 40For he that is not against us is on our part. 41For whosoever shall give you a cup of water to drink in my name, because ye belong to Christ, verily I say unto you, he shall not lose his reward.
It doesn’t say they were preaching another gospel.
Ah!
We have a Reader's Digest bible scholar on our hands!