Since 2013, the number of people across the Arab world identifying as "not religious" has risen from 8% to 13%. The rise is greatest in the under 30s, among whom 18% identify as not religious.
The trend in North Africa is significantly greater than the rest of the Arab world. Iranians aren’t Arabs, they’re Persians, but it would be interesting to know the trend there. I think the drift to secularism in Iran would be even greater in response to an oppressive Islamic regime.
Another indicator of rising secularism in the Arab world is the declining fertility rate. In general, the more religious you are the more children you have, the more secular, the lower the fertility rate. Forty years after the Islamic Revolution, Iranians are disillusioned with Islam and becoming secular. They’ve also become the most responsive people to the gospel on the planet. Perhaps the same trend is emerging in the Arab Muslim world.