Are the false teachers Christian? Were they ever Christian?

It is not possible to definitively determine whether someone is or was a true Christian, as only God can truly know a person's heart and faith. However, false teachers are typically individuals who claim to be Christian but promote teachings that are contrary to the core beliefs and principles of Christianity. They may have at one point identified as Christian or been part of a Christian community, but their actions and teachings ultimately lead others away from the true message of Christianity.