He has been speaking at a press conference in Los Angeles ahead of the release of the movie Exodus: Gods and Kings, in which he plays the lead role.
Speaking about his portrayal, Bale said he undertook detailed research into the life of Moses, including reading the Bible, Torah and Koran, and that he was surprised by what he found.
He said: "I think the man was likely schizophrenic and was one of the most barbaric individuals that I ever read about in my life.
"He was a very troubled, tumultuous man and mercurial. But the biggest surprise was the nature of God. He was equally very mercurial."
The comments have been criticised by Christian writer and film expert Brian Godawa.
Writing on his blog about Bale and the recent Hollywood version of the story of Noah, he said: "First a Noah who is an environmentalist whacko vegan animal rights madman with delusions.
"Now a Moses who is a schizophrenic barbarian?
"I only hope that the comment is more a reflection of the actor's own ignorant bigotry than of the actual movie."
The movie is due for release in December.
Watch the trailer here: