Islam is the spirit of Antichrist. That God opposing spirit, that has always been there, took a political form in Islam. It’s power is deception and lies combined with political oppression against other faiths.
As 2. Thessalonians 2:10-11 describes:
... with all the deception of wickedness for those who perish, because they did not receive the love of the truth so as to be saved.
And for this reason God will send upon them a deluding influence so that they might believe what is false.