I disagree...
There are three separate bodies within the York path; Chapter, Council, and Commandery. Only Commandery has religious requirements. I know a number of Brethren who are quite active in Chapter and Council who aren't members of Commandery due to their beliefs. I also know Brothers who could be in Commandery but aren't. Frankly, they can't stand the uniforms.
Don't let the Commandery requirement keep you from pursuing your Mark or the Royal Arch.