Freedom OF religion means that the state should not impose yours on my children.
Impose WHAT religion? Tell me, specifically, what religion (Catholicism, Bhuddism, Santaria, Wicca, Scientology) is being imposed upon your children when a teacher leads the Pledge, and how it is being imposed, seeing as how they have the freedom to not say it.
If your argument is that "well my children are athiests", then obviously God does not exist, therefore your children are being harmed by nothing. Do you freak out in the supermarket and cover your children's eyes when you see a box of Lucky Charms? After all, the store is imposing it's belief in leprechauns.
Since this republic is founded on the notion that our rights are endowed by our Creator and our system of government and it's Constitution are blessed by our Creator, aknowledging the same is, by definition, Constitutional. The Constitution rests upon the Declaration of Independence. The two are inseparable, or else they mean nothing.
The Pledge will prevail, the famously overturned 9th not-whitstanding. Any mealy mouthed ungrateful little brats that don't like it can just wipe their snotty noses and shut up.