Here's a full text of his speech. Like others, I have a problem with this: "Freedom requires religion just as religion requires freedom. Freedom opens the windows of the soul so that man can discover his most profound beliefs and commune with God. Freedom and religion endure together, or perish alone."
Sentence 1 I don't buy. I know personally atheists who are big enthusiasts of freedom, and who practice it. Indeed, Ben Franklin was pretty close to being an atheist, and he certainly promoted freedom.
Sentence 2 is well-put.
Sentence 3--well, maybe. I suppose this fits within Frank Meyer's old tried-and-true fusionist thesis: that we must seek the True and the Good. But the True and the Good is only worth anything if it is freely chosen; and freedom, without some sense of God and morality, can easily sink into libertinism. Maybe that's what Romney was getting at.
Still, suggesting that freedom REQUIRES religion is rather untenable ground.