Turkish President Tayyip Erdogan used the Gulen movement as allies to gain power. However, once in power, Erdogan turned on Gulen, attempted to purge his followers from the police and judiciary, then used the movement as a "fifth-column" type scapegoat.

secularism in Turkey was born at the point of a bayonet. [..] Turkey's government is both secular and democratic, due to the founding father of Turkey, Kemal Ataturk. While Ataturk was a brutal dictator, he also used that power to rebuild a Turkish national identity, secularize the government, and eventually transition to democracy.

As many news sources have pointed out, the military sees itself as safeguarding the vision and (secular) state structure of Ataturk, and regularly purges the government when its leaders violate Ataturk's premise.

So it is most likely that the coup is secular in nature, and it is Erdogan's spin that is blaming Gulen.

I think the coup is related to the recent position of Erdogan towards Russia.

All this happened in the space of a few weeks. It was such an about-face from their past postutring. I guess this puts things in context.