I recall when I was young the uproar that occured when Pat Boone joined the "Charismatic movement" that includes speaking in tongues, faith healing, etc. There were books published by the Church of Christ saying he was no better than a Catholic in his godlessness. They didn't mention Mormons, but then I don't think Mormons were on anybody's radar back then.
Hmm, well, I don't know anything about that, but I go to a Church of Christ in California, and I think you'd find it impossible to get any of the elders in the church to automatically damn all Catholics to hell.