Here are 5 problems that arise when one denies free will.
1 – It makes God the cause/author of sin.
2- It makes God a monster playing us all like a game of chess. Making some do good and others do bad like raping children.
3- It takes away the responsibility of the sinner and makes sinners innocent.
4- Life is an illusion and not really real.
5- It makes God a liar and the bible false because he is not really being relational to humans like the bible shows us.