My remarks about how some Christians make Christianity into idol worship needs to be concluded.
The main issue to be tied up is whether the problem of idolatry could in principle be resolved if the would-be Christian is sincere enough in his faith and belief. Idolatrous worship is not a matter of sincerity. Sincerity is something that other people judge of one another. It most certainly is not something that one can ascertain of one's own belief with any hope of integrity: the motivation to appear good & righteous in one's own eyes is simply too overwhelming. The struggle to overcome doubts of one's own sincerity results in an oscillations between the extremes of an overweening piety and an overweening feeling of sinfulness.
The issue of sincerity can be rephrased as authenticity vs. inauthenticity. Or more colloquially as "real" Christianity vs. "fake" Christianity. Or in terminology found in the New Testament: uncircumcised Christians vs. circumcised Christians, and Christians of the spirit vs. Christians of the flesh.
Attempts to resolve the idolatry issue by an appeal to sincerity and "true" belief presumes a number of things. First that there is a difference between sincere and insincere belief. Both sincere and insincere belief are attitudes towards one's own belief. When a believer becomes anxious about his belief, he is no longer living and feeling from within his faith. It is the difference between loving someone and speaking of one's love. In becoming anxious about his faith, the believer is no longer consumed by faith and the putative object of his faith. The believer feels himself cut off, cast out, and most vulnerable to seeking the how & why of his faith and belief.
At such moments the believer faces a most insidious temptation: judging his faith by the standard of quietude: the less troubled the believer is by objections the greater the faith. Faith then becomes a means to self-diminution and a means of avoiding engagement with the world that the believer's creator-God spoke into existence.
The end result is that faith in God, in the literal veracity of the New Testament, in whatever, really, becomes a means to an end. God is no longer a person for such a one, God is a means to the end of spiritual quietude and avoiding engagement with God's creation. God is then loved not for who He is, but for what he has to give. The believer becomes a spoilt child of God: the believers love the fount of Creation for occasional blessings bestowed. Consequently, there is also fear lest this fount dries up. In religious language: God might turn His face away. With fear comes bargaining: one "believes" in God so that God would not take away blessings already bestowed. Such a one is no Christian, but a mere believer. He might as well be a new-ager, a follower of Asatru, scientology, or whatever, the criterion of "true faith" is not truth and integrity but the extent to which the belief-system is able to give peace and disengagement from all the unexpected events of the world around him. A believer loves the effect of his faith, not the professed object of his faith.
It also follows easily enough why idolatrous believers are prone to violence. Any questioning, any requirement for thought is a threat to the promised comforts of their spirituality. They eat not for enjoyment of food but for the absence of hunger that eating brings. For Freud, the difference between a neurotic and a psychotic is that the psychotic denies reality in toto, while the neurotic only denies a piece of reality. Whatever faith might have been, it is now a synonym for neurosis.
Honest Christians are in principle possible, but are short-lived creatures. When the moment of truth and crisis of faith comes, another cannot say. Before that moment comes, before the realization comes that faith is questionable, it is possible to speak of authentic faith, but an authentic believer cannot know that his faith in God is "authentic." Once he does, the sincerity of his faith disappears in a puff of questions and uncertainties.