All false beliefs come from man when he/she decides that there is more truth then what is contained in God's words and that God is speaking to them beyond "It is written".
What causes false theology, that leads to false doctrine and eventually turns into a new cult ?
1.) Someone who is not actually born again becomes obsessed with the bible, and becomes very religious but lost......and creates a theology that sounds spiritual, and sells it as truth.
This very forum, has one of those on it.. who teaches that "The Cross is not about forgiveness". And their personal salvation testimony, has nothing to do with the Cross of Christ, or Faith in Jesus, or their sin being forgiven.....nothing., nothing, nothing.
And usually this type of deceiver
FAKES some type of mystical sounding speech, or they say they received their theology from an angel or similar voice or vision... ect, ect.
So, many people are fooled by this type of "dark" speech, so, they become a follower, or disciple.
2.) False theology is created by people who do not "rightly divided the word".. (Paul's verse).......so, they just get in there and try to make it all fit together when it doesn't.......and what they end up with is "wrongly divided" false theology.
How do you avoid them, and how do you avoid becoming one of those.
Its very simple.
Learn Paul's Gospel, and Learn Paul's Theology......and stay there for life.
Paul gave to the "body of Christ" "The Church"..... the Doctrine for the Church, after Jesus personally gave it all to Paul, after Jesus was resurrected and back in Heaven.
So, when you learn Paul's teaching.. his "doctrine"...then you've become what Hebrews 13:9 says that you have to do with your heart, or a "doctrine of devils" is going to capture your mind and deceive you.... Reader.