You know these things for sure??..
They are guilty of "idolatry"???...
Allah is their conception of God, not a prophet. Muhammed is the prophet and he is a liar.
Buddha is a false teacher. I don't know that he prophesied anything (i.e. predicted the future).
Imo, before you make such statements, you should make "damn" sure you are right. Especially when it comes to those of such profound historical and theoretical significance - like Buddha, Allah, or Jesus..... It is the epitome of arrogance to believe you are "right" and the majority of the world's population is wrong..... What if the "right" is wrong?....
Just something to think about!..... :)