According to Islam, your own ancestors before Muhammad all worshipped demons, worked with demons, and these demons drew them into sin and evil, sending them to hell.
No just and loving God would ever allow this. No just and loving God would hide his message until some prophet came, or even send people to hell for simply not knowing about him, when he only spoke to certain prophets in one corner of the world.
The beings that your ancestors worshipped and communicated with are indeed real, and did indeed teach humanity. They were never evil, and the true "Allah" (Al-Ilah, "the greatest") is Zeus. God would never feel the need to set himself arbitrarily above "creation" or other beings that may be lesser than him.
Islam lied about God, and the "demons" never taught or demanded anything evil.
You know this, and it is normal to be afraid when you've been told otherwise your entire life.
If you come here and are even slightly considering Zevism, you already know that "Mohammad" and all the creators of Islam lied about Allah.
Study, meditate, do the Rituals, all of this would obviously help. But if you're in a position where you are too afraid to even do these things, I have a piece of advice.
Ask Allah.
Go into prayer, and state your fears to God. State why you think Zevism might be true, what parts of Islam hold you back and so on. You can even call Him Allah, the name is fine.
Ask to be guided into what the truth is. Trust that you will.