Well, there are several false conclusions being drawn here:
- Because Christianity is not true, God therefore is not real.
- Because God is not real, there cannot be any spiritual entities.
If you are not careful, this can quickly lead to:
- Because there are no spiritual entities, there is no afterlife.
- Because none of this exists, psychic abilities are not real.
You may or may not believe in a God. Certainly there are other belief systems with one or many gods. You may even just believe in a creative force behind everything, as would most closely identify my beliefs.
However, it remains, even if there is no God, it does not mean that spiritual entities cannot exist. I mean, physical entities still exist, right? And if physical entities exist, then non-physical entities may also exist. If non-physical entities may exist, they may certainly be across the spectrum from positive to negative—i.e., angels and demons, and everything in between.