The GOP needs to decide if they are a political party of religious commonality; or a political party with similar political views. If it's religion, then your observation holds true, and the party will fade away due to lack of members as it offends and repells non-Christians. If it's political, then they need to couch all their stands, and their rituals, in political terms that various groups can agree with.
We beleive in a federal government that is forever limited to spending no more than 10%, or 5% or 1% of the national GDP.
We beleive in a federal government that is restricted to a maximum of 10,000 pages of legislative rules and regulations; regardless of how many departments and agencies there are.
Something of that sort.