Just so there is no confusion, this is what the First Amendment says:
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
Additionally, not all speech is protected unconditionally. Yes, you are free to say what you want, but you may still be prosecuted afterward for what you say based on all sorts of other laws. Examples include libel, slander, "fighting words", sincere threats of violence or death, perjury, extortion, use of child pornography, certain forms of obscenity, certain forms of harassment, copyright infringement and regulations regarding how speech may be used for demonstrations.
The First Amendment, like the Second Amendment (and others) doesn't end at the whim of whatever interpretation is convenient for purposes of a conservative agenda. It's common for the general public to misinterpret Constitutional law, but unfortunately, Congress often overlooks it as well without being challenged. For example, gun enthusiasts love using the Second Amendment as a shield saying that it is their Constitutional right to own guns. So, they layer interpretation of the Amendment with a convenient assortment of excuses to mean something more general than what it actually says, forgetting that there are already laws in place that prevent the ownership not only of certain types of guns, but also other various forms of "arms" or weapons. They also often apply originalism inconsistently and with intentional ignorance.
So, when invoking the Constitution, it's probably best to explain whether your intent is to apply it as it is currently interpreted and enforced, taking it literally, approaching it from an originalist ideology, or just talking out of your ass based on the popular rhetoric of a political ideology which is often not based in legal research.
"What can you expect from a bunch of seitan worshippers?" - Reginald Tresilian