Hezbollah, Hamas, al-Qaida, the Muslim Brotherhood, the ayatollahs, Jamaat-e-Islami in Pakistan, the Taliban and all the other Islamist organizations actually decrease the number of believers in the world.
Over the course of time, people do not judge religions by their theology. Yes, some people convert to a religion thanks to its convincing theology. And many remain in a religion because of family ties, cultural norms and sheer inertia. But over time, religion — and faith in God itself — is judged by its fruit. Which is how it should be.
And the best known fruit of Islam today — countries calling themselves Muslim, such as Iran, Saudi Arabia, Pakistan and Taliban Afghanistan, not to mention Islamist groups — is so ugly that many millions of people are increasingly repelled by religion and by God.