It's not just aspects of predestination that is error there are other things
I believe it is blasphemy to say that Jesus only died for the elect - it makes his sacrifice third class if he didn't die for the whole world
God shows his Greatness and Love by dying for everyone even those that hate and reject him - that is the measure of greatness, to die for the ones who will still reject you
Calvinists want to proclaim and defend God's greatness but they actually denigrate it by stating he did not die for the non-elect
That is a huge deception in their teaching