The right to free speech does not protect your right to commit crimes or civilly damage someone merely by speaking as part of the crime or tort. So if you and your friends plan to rob a bank together, the planning, or conspiracy, can be a separate charge in addition to the robbery. Libel is a tort because you lie (important) to damage someone's reputation and this could cost them money.
Hate speech is mostly just hurting peoples feelings. It neither helps cause physical damage nor costs the victims money. You cannot, in the US, ban the expression of a thought just because you think somewhere down the line it could result in damage to someone.
So three guys conspire to burn down a church- that could damage someone. A guy writing on the internet that churches are full of pedos and someone who reads that decides to burn down a church? The guy who burns the church only committed a crime.
There could be grey areas between those two situations and that is for law to decide. But the crime cannot be essentially the thoughts and ideas expressed