The title of the OP is the topic of this debate. I believe...
What you believe has no bearing on the truth of the matter.
...that the seven nations listed in the temporary ban had nothing to do with religion as much as it had to do with "hot spots" around the world where terrorism id running wild.
The seven nations do have problems with terrorism. So do some countries that are not included in the ban. In fact, outside of homegrown terrorism, countries not included in the ban have been responsible for acts of terrorism on U.S. soil.
But beyond that issue, the ban DOES have something "to do with religion" that makes it unconstitutional. The ban was written to cover seven Muslim-majority countries, but only allows exemptions to those who are not of the majority religion (Islam):
Sec. 5. Realignment of the U.S. Refugee Admissions Program for Fiscal Year 2017.
(b) Upon the resumption of USRAP admissions, the Secretary of State, in consultation with the Secretary of Homeland Security, is further directed to make changes, to the extent permitted by law, to prioritize refugee claims made by individuals on the basis of religious-based persecution, provided that the religion of the individual is a minority religion in the individual's country of nationality. Where necessary and appropriate, the Secretaries of State and Homeland Security shall recommend legislation to the President that would assist with such prioritization.
Therefore, it results (as intended), to limit consideration for refugee status to those who are non-Muslim. It is definitely a Muslim ban. Moreover, Rudy Giuliani has stated that President Trump asked him how to create a Muslim ban, and he had a large hand in crafting the order.
So from a simple reading of the text and the testimony of someone who was apparently involved, we have a ban on refugees based on religious affiliation.