Secularism and pluralism are two of the defining ethos of Western societies. The former decouples religion from governmental institutions whilst the latter seeks to protect the rights of all citizens to freely practice their creed. In many instances, these two concepts can happily coexist. Problems however arise in one of two instances: 1) When the practice of one's religion seeps into the public sphere and in so doing violates the right of others to be free from religion (e.g., prayers in public spaces); 2) When the supposed private practice of one's religion harms third parties (e.g., withholding medical treatment from your child). Let us look at each of the two situations in turn.
Suppose that you attend a public secular school. To demand that some or all of the food offerings conform to your religious beliefs is unacceptable. This is an intrusion into the public sphere that is an affront to the definition of secularism. If one wishes to forgo the protection afforded by secular pluralism then perhaps Western liberal democracies is not the right place for you to freely exercise your religion. The reflex of many well-meaning people is to argue that it is important to be "tolerant" and "accommodating." Secular societies establish tolerance by being equally non-accommodating toward all religious demands within the public sphere. What you believe in the privacy of your thoughts, and what you do in the privacy of your home or house of worship is your business. What you do in the public realm is our collective business. In the public realm, secularism should not concede a single inch to religious intrusions. To argue otherwise is to violate the meaning of secularism. You cannot be a virgin and a porn star. You cannot be an atheist and a believer in God. Similarly, you cannot "sort of" be a secular society. It's an all-or-nothing proposition. A confident culture defends its foundational tenets. Many people have emigrated to the West (my family included) in order to be free of religious persecution. It is the tenets of the secular society that have afforded us these freedoms, each of which is slowly being challenged by a growing threat from religious fundamentalism.
Let us move next to the second example, namely when the "private" practice of one's faith harms a third party. A child does not choose the family in which he/she is born. If it happens that a child is stricken with a disease that requires specific medical treatments that are otherwise forbidden by the parents' religion, the rights of the child to be cured supersede those of the parents. If marketers are not permitted to target very young children with advertisements, it stands to reason that the same children should be protected from the nefarious beliefs of their parents. Persuading children to purchase your brand of chewing gum is apparently strictly forbidden, but altering if not outright withholding medical treatment from them, or having them experience horrifying genital mutilation (in the name of your faith), well that's just "multicultural" and "tolerant."
The position that I am enunciating here is not "anti-religion." Practice your religion to your heart's content as long as it does not violate the rights of others in any way. This is the means by which the rights of all citizens in a free, secular, and pluralistic society are protected. Once we begin to grant special privileges and accommodations to some (typically those whose religious beliefs dictate an intrusive presence within the public realm), we head down the proverbial slippery slope from which it is difficult to recover.