"The idea that if you take religion out of the public square, if you take the Bible out of the classroom, that that’s neutral - well, no it’s not neutral! It’s a different worldview.“

I partially agree.  Schools should conduct a survey of religion(s) Nobody is taking your religion out of the public square. People are however, opposing the government endorsement of religion, writ large. And I'm really not sure how one teaches secularism in school.

“I think we should start calling secularism a religion.”

I think people should call you a dumbass. There, see how that works?

“Because if we did, then we could ban that too, because that’s what they’ve done.“

And, no. Religion cannot be banned. Religion is the faith and practice regarding supernatural [and naturally invisible] deity, by individuals.

“They’ve hidden behind the fact that the absence of a religion is not a religion of itself, which, in fact it is, because it has certain moral values and certain teachings that look like a type of moral worldview.”

Make up your mind…you just called the absence of a religion NOT a religion..and then contradicted yourself. A secular “worldview” professes a paradigm where the State [the government of ALL American citizens in this case] does not officially endorse the existence of a supernatural deity…much like our Constitution.

“So what we have to start doing as Christians is reassert ourselves and say, 'You know what? The freedom of religion is not the freedom from religion.”

Somewhere a bumper sticker has lost its catch-phrase. Freedom OF religion likewise does not mean a government endorsement thereof…it means that all citizens are free to practice a religion of their choice, or none.

“We should be in the public square. We should be taught in the schools. We should be an open marketplace of ideas instead of throttling one perspective out of the fear it being offensive to someone."

Uh-huh. The public square and marketplace of ideas occurs when like minded citizens form voluntary associations. When the State takes a stand on a controversial and utterly unprovable issue such as religion, it opens the gates for a majority oppression of certain ideas..as we’ve seen in the past.

An astute commenter at the link below noted: Secularism isn't the presence or absence of belief. It is the act of not taking a position on religion where one's personal views on religion are not at issue.
Mediate

Of course, Santorum travels in the same circles as Bryan Fischer:

Military service should rightly be reserved for those who believe in and are willing to die for what America stands for - and what America stands for is a belief in God as the source of our rights.