An interpretation of the fictional account of Jesus says that he "taught that we must die unto ourselves, and allow the Holy Spirit to take up residence within us."
People fool themselves into believing that they "get saved by simply inviting Jesus into their hearts, to be the lord of their life." They allow ancient fiction to dictate their morality as they think obedience to ancient fiction is "a countering force within" them "to counterbalance the will of the flesh." You know- normal desires of normal people.
To ensure that Christian churches maintain membership and monetary gain, the churches of various beliefs have this in common- They teach that:
Attempting to live the Christian life without having this spirit within you is a waste of time at the minimum, and dangerous on the downside.
Most folks would agree that the New Testament claims that the resurrection of Jesus is "a well attested fact of history," and that most Christians accept it without a shred of proof.