Depending on what your purpose is. If you want to eradicate a specific religion, you would promote it as the only religion. Religion for some strange reason, i.e. power, brings out the worst of competitive nature. After the original concepts of the religion are dismissed in favor of power, the downward spiral begins. If there is no other religion to compete against they will turn inward and devour each other. Why else would there be so many denominations within the christian church.
If you want to live a happy life then you would definitely choose a secular country.