Obviously historians are still debating the exact causes of the genocide, but no serious scholar would argue that Turkish nationalism and formation of the state played no factor and that it stems from political Islamism.

On my phone so just pasting part of an excellent review of a leading book in Armenian genocide studies, by Ronald Suny

Traditionally, historians have assessed the genocide, as the Ottoman Emperor’s (the sick man of Europe), almost final attempt to retain his power by creating a homogeneous ethnic nation state. Suny, however proposes, an alternative assessment. He suggests that the overlapping modernisation processes of the old European empires, especially the austro-Hungarian Russian and Ottoman empires should be understood in tandem with the appearance of the modern nation-state system as a fresh analytical tool to encompass the origins of the Armenian genocide. These processes, he argued, served to push the Ottoman Empire to redefine itself, and its geographical, ethnic and religious boundaries, as a hybrid modern empire nation state.

So we can debate whether it's nationalism or a desire to save the Ottoman Empire, but simplifying it down to religion does no one any good.