God through his Word has commanded His people to test the spirits since there are false teachings and false teachers.
It would be irresponsible not to do so. Since Mormons do not profess the truth about the nature of God and claim they will be gods themselves, they are not Orthodox, though they claim to be.
“do not profess the truth about the nature of God”
OK. who is it, exactly, that knows the truth about the nature of God?
Did God give that person, that group, written endorsement?