Interestingly, our Founding Fathers understood the necessity of separation of powers, as otherwise, religious conviction could subscribe duties that were beyond conscethe individual's conscience, in fact, in spite of our conscience.
The civil government was to bring order and structure, but was not to mandate how one lives one's life. When "social realities", which are created by those who rule, are driven by absolutist' s opinions, traditions, or values, then the individual looses his own personhood in the name of and for the sake of the "Almighty" ( who just happen to be those in power).
Separation of power was not only the intent of the government to separate ruling by religious tradition, it was also to balance the civil powers, so that there was accountability. I find that this is a necessity especially in today's climate of "leadership" driven models, where power is sought at the costs of rationality and moderation.
I think that both separations should be maintained to uphold the individual's right and the rule of law, which supports decent order and structure.
Otherwise, it is Repent OR Do Penance.....OR Perish!