Islam is the religion of Arabs whether we like it or not. If you believe like an Arab, If you feel like an Arab, If you trade like an Arab, If you pray like an Arab, If you wear clothes like an Arab you are indeed an Arab. Not that this is a bad thing. Being Arab is perfectly fine nothing wrong with that. But forcing others to become Arab is the wrong part. Mr. Ali Erbaş is exactly doing that. Today he told that we should use economic and trade rules of Arabs, social traditions, and rules of Arabs, we should use the laws of Arabs, etc.
You are right on the god part. Old Turkic beliefs are somewhere between deism and pantheism. We even twisted sharia of Islam to suit our needs because of those roots.
Well all it mattered for Turks is can we go to war so we can raid and loot.
Also monotheism is great for uniting a people under one banner.
1 God
1 Empire
1 State
People are also forgetting how Tengrism was embedded in the state. Khans always had Shamans with them.
Also the Turks went to war as a punishment to humanity. I dont mean tengrism was a full blown theocracy but the religion still played an important role for the Huns, Mongols, Gokturks, Avars, Khazars and the Bulgars.
You cant apply modern day concept of secularism on the Pre Islamic Era or the post Islamic era as religion was important no matter what.
Seljuk Turks actually helped Sunni Islam become a reinsurgent religion when the abbassids were declining and under the thumb of various shia dynasties.
People dont realise this but Arab domination in Islam has gradually declined as the Turks, Amazighs and Persians took control of their respective regions.
Same story with Al Andalus the Arabs declined and gave way for Berbers.
Still with decline it did not put a dent on the Arabisation of the middle east and north africa.