Does freedom of religion also mean freedom from religion?

Decidedly yes, insofar as the rights of those who choose not to practice any religion. The First Amendment provides for freedom of religion for those who choose to follow a particular religious belief. There is nothing anywhere in the Constitution, the Declaration of Independence, the writings of the Founding Fathers, or the laws of this nation that requires any citizen to espouse a religious belief or that, conversely, disallows unbelief (atheism). Thomas Jefferson said:

"The legitimate powers of government extend to such acts only as are injurious to others. But it does me no injury for my neighbor to say there are twenty gods or no God."