The man in Belgium who attacked two police officers with a machete cried that his 'god is great'. The God of heaven is indeed great, but He does not require, approve, condone or desire the harming of human beings to prove, demonstrate, advertise or remind us of His greatness. Within the Decalogue He forbids the unlawful killing of people. The man who performed this evil act has just appeared before the eternal Judge to stand trial for his crimes.
If your god, gods, prophets, priests, gurus or even your own fevered imagination tells you to hurt or maim another person, change your religion fast or seek psychological help. The God of Heaven and Earth would never command such a horrid thing. Only the 'god' of this world would revel in such atrocity. He is not great, and his days are numbered. Come, Lord Jesus!
In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them 1 Corinthians 4:4.