The Scriptures make no mention of the "Real Presence", so the issue is of man.
Well, I am not sure how you interpret "this is my Body broken for you; this is my blood poured out for you" as anything other than the Real Presence. The fact is, to claim otherwise is to deny scripture, the beliefs of the Early Church, the Church Fathers, early theologians like Augustine, 1500 years of united Christian belief, and even Reformers like Luther and King Henry VIII (modified belief). My point is, that what you see so clearly in scripture is a new idea in Christianity.
But, if you want to persist in this new belief, it is your choice. So here is my question; why would anyone who doesn't share in the beliefs of a practice, want to share in the practice?
Jesus nor the apostles make mention of this so I don't see how the Catholic church and can it is idolatry to not believe it.
You must be forgetting Paul's warning about taking the Eucharist in an unworthy manner. It is indeed idolatry to participate in worship, which includes anything, but God as its object of worship - taking the Eucharist in the Catholic Church is worship. In fact, many Catholics participate in the Holy practice of adoration of the Eucharist - it is also an act of worship.
Now, I realize that the Catholic church believes in continuing revelation which the Scriptures do not support. I suspect that is where they get the authority for this claim.
Hmm...actually I think you do believe in continuing revelation; the teaching of sola scriptura is an example of continuing revelation - it is only 500 years old. The strange thing about the Reformation is that it really didn't reform anything - instead it replaced Catholic tradition with 10,000 varieties of Protestant traditions.
No, the foundation of the Christian church is not the Trinity. It is "Jesus is the Christ" the Son of the living God. The promised Messiah of the Old Testament.
Actually, your statement is part of the doctrine of the Trinity. The doctrine of the Trinity describes the full and true nature of God. Any person or group that denies the doctrine of the Trinity, denies God's true nature and is therefore outside the definition of a Christian. All heresies start with a warped view of the nature of God.
I don;t know that you could classify Mormons as Christians, I'm not that familiar with their beliefs.
Mormons have a rich tradition of heresy, but the only really important thing to know for this conversation is that they deny the Trinity.