Ok, take the Heavenly Destiny doctrine. It says that believers go to Heaven when they die. That teaching is not taught anywhere in Scripture. The modern teaching of the Trinity, that there are three co equal beings in the Trinity. Jesus said the Father is greater than. I've spoken with many who believe that the Trinity consists of the Father, Son, and Holy Spirit and that three these are God. They then speak of God using singular pronouns such as He and HIm. That idea is a logical contradition. Three persons cannot be one being, that's impossible. However, I have see people argue till the cows come home that this is the Trinity. It is not. It's a doctrine that came about in the 5th century and I believe Augustine had a lot to do with it. If we look at what the church believed prior to that such as in the Nicene Creed we find that they believed what the apostle Paul said,
6 But to us there is but one God, the Father, of whom are all things, and we in him; and one Lord Jesus Christ, by whom are all things, and we by him. (1 Cor. 8:6 KJV)
Then there is the doctrine that there is some part of man that lives on after his death and is conscious somewhere, whether it is in Hades, Abraham's bosom or Heaven etc. The Scriptures tell us plainly who God created man in Gen 2 and what happens to man when he dies in Ecc.3. Gen 2 says that God created the man from the dust of the earth and breath into him the breath of life and man became a living soul. So,man is a living soul that consists of a body and the breath of God. Ecc.3 tells us that when a man dies his body goes back to the dust and the breath returns to God. So, there is nothing left to live on after death. Yet, in spite of this clear teaching in Scripture many Christians simply look right past it and continue to argue for the doctrine.
These are three of the big ones and a serious study of them shows that what many claim today simply isn't what the Scriptures teach. If you want to look into them we can.