The Compendium of the Social Doctrine of the Church has this to say about religious freedom:
"Freedom of conscience and religion 'concerns man both individually and socially.' The right to religious freedom must be recognized in the juridical order and sanctioned as a civil right" (422).Practically speaking, this is necessary because religious belief cannot be coerced: it is impossible for anyone except God to know a man's heart, and consequently any such coercion is simply unenforceable beyond extracting external signs of compliance from someone. More importantly though, a human act is one that is both free and deliberate. But if religious belief is coerced, then it is not free; consequently it is not a human act. But religious belief by its very nature is the most important sort of belief that one may have. Hence it is a grave violation of a person's standing as a human being to rob them of that liberty of belief. Thus we simply must stand for religious freedom.
This is not to say that we must approve of the content of each man's beliefs. Granting the liberty does not imply endorsement.
Likewise it is not to say that we must tolerate everything in the name of religion:
The just limits of the exercise of religious freedom must be determined in each social situation with political prudence, according to the requirements of the common good, and ratified by the civil authority through legal norms consistent with the objective moral order. Such norms are required by "the need for the effective safeguarding of the rights of all citizens and for the peaceful settlement of conflicts of rights, also by the need for an adequate care of genuine public peace, which comes about when men live together in good order and in true justice, and finally by the need for a proper guardianship of public morality" (ibid.)We are not obliged as a society to endorse temple prostitution, for example.