Having a God does not mean you have a God. It could be an idol. Ideology is the power of the idea - the idea becomes all that matters. It is elevated to God. And anybody who opposes it is evil and should not be allowed to speak.  The idea becomes a makeshift God.  Its not a real God.  But it is real in its terrible consequences. 

If it is a God substitute as some would say then surely that means God is not a good belief in the first place?  If you need a God and there is none then what you end up with need do no obvious harm to others?  Suppose there is a God. Having the wrong God means that it is harmful to disconnect from the real God as in failing to get help from him or more sinisterly the real God is making sure you will suffer for not having him.  Suppose there is no God.  Then God is as dangerous or otherwise a belief as any substitute.  We need to ask why belief in the tooth fairy harms nobody but belief in God has its sincere extremists who are very harmful.  The problem with the belief is that it is a projection towards a supreme power.
In Jungian thought, if you take doctrines and religious symbols seriously and literally that is a form of idolatry.
Taking them seriously is a bigger giveaway than literally. Literal beliefs that should not be seen that way are one thing but they become a problem just because they are taken seriously.
You know that God is not literally a wafer and if you treat the wafer as God as in the Catholic Mass that is best seen as an attempt to take it literally. You cannot really be insane enough to succeed. You cannot really see God as a man in the clouds either. Taking symbol seriously then is more intelligent but more subtly and dangerously idolatrous.

God cannot really be thought of without symbols. Using nothing or refusing to use images does not fix the difficulty for nothing or a void can be a symbol too. A symbol is anything you use to represent something. In fact using the void or nothing as a sign of God is the biggest form of idolatry.  Its the best for it is so crafty. 

The problem is insoluble and thus shows that if there is a God he is not about having a relationship with us.