Why don't you want your government to rule religiously if religious people share your values?
Because it has never worked well in the past in the west, or anywhere else in the world (a contemporary example is the Islamic Republic of Iran- not sure we should give up western secular democracy and use their model as a guide).
Why don't we ask this question of the founding fathers of this country, who had experienced nations who had worked that way for a long time, and were eager to get away from it when they set up this country?
"It was the belief of all sects at one time that the establishment of Religion by law, was right & necessary; that the true religion ought to be established in exclusion of every other; and that the only question to be decided was which was the true religion. The example of Holland proved that a toleration of sects, dissenting from the established sect, was safe & even useful. The example of the Colonies, now States, which rejected religious establishments altogether, proved that all Sects might be safely & advantageously put on a footing of equal & entire freedom.... We are teaching the world the great truth that Govts do better without Kings & Nobles than with them. The merit will be doubled by the other lesson that Religion flourishes in greater purity, without than with the aid of Gov. "
"During almost fifteen centuries has the legal establishment of Christianity been on trial. What have been its fruits? More or less in all places, pride and indolence in the Clergy, ignorance and servility in the laity, in both, superstition, bigotry and persecution...In some instances they have been seen to erect a spiritual tyranny on the ruins of the Civil authority; in many instances they have been seen upholding the thrones of political tyranny: in no instance have they been seen the guardians of the liberties of the people. Rulers who wished to subvert the public liberty, may have found an established Clergy convenient auxiliaries. A just Government instituted to secure & perpetuate it needs them not.”
"The purpose of separation of church and state is to keep forever from these shores the ceaseless strife that has soaked the soil of Europe in blood for centuries...Who does not see that the same authority which can establish Christianity, in exclusion of all other Religions, may establish with the same ease any particular sect of Christians, in exclusion of all other Sects?"
"The experience of the United States is a happy disproof of the error so long rooted in the unenlightened minds of well-meaning Christians, as well as in the corrupt hearts of persecuting usurpers, that without a legal incorporation of religious and civil polity, neither could be supported. A mutual independence is found most friendly to practical Religion, to social harmony, and to political prosperity."
"Mingling religion with politics may be disavowed and reprobated by every inhabitant of America...All national institutions of churches, whether Jewish, Christian, or Turkish (Muslim), appear to me no other than human inventions set up to terrify and enslave mankind, and monopolize power and profit."
“Of all the systems of religion that ever were invented, there is no more derogatory..., more unedifying to man, more repugnant to reason, and more contradictory to itself than this thing called Christianity. Too absurd for belief, too impossible to convince, and too inconsistent for practice, it renders the heart torpid or produces only atheists or fanatics. As an engine of power, it serves the purpose of despotism, and as a means of wealth, the avarice of priests, but so far as respects the good of man in general it leads to nothing here or hereafter.”
― Thomas Paine
"History, I believe, furnishes no example of a priest-ridden people maintaining a free civil government. This marks the lowest grade of ignorance of which their civil as well as religious leaders will always avail themselves for their own purposes."
"They [the Christian clergy] believe that any portion of power confided to me, will be exerted in opposition to their schemes. And they believe rightly; for I have sworn... eternal hostility against every form of tyranny over the mind of man. But this is all they have to fear from me: and enough, too, in their opinion."
All national institutions of churches, whether Jewish, Christian, or Turkish (Muslim), appear to me no other than human inventions set up to terrify and enslave mankind, and monopolize power and profit."