That statement makes no sense. The man is sincerely expressing his view and the church’s doctrine on a divided church. Does your church make no claims to have a better theology than others. Does doing so mean it is trying to drive people away or to rather calling people to what it believes is the truth?
However, since you think it’s okay to speak down to fellow Christians then it seems to me that the Greeks would be most likely to have Christianity the most correct since the scriptures were ultimately written in Greek and not Latin. This is only one reason.