Sure you can. Not in Germany or in France, but people wear Nazi symbols, get Nazi tattoos, fly Nazi flags all the time in the U.S.
The only speech that needs protecting is offensive speech. So if you see something that offends you, it is probably protected, otherwise, what would be the point of Free Speech?
As a practical matter you cannot. My friends did, and got a visit from the FBI. That was a long time ago.
This is not free speech. ISIS is a declared enemy of the U.S. and our Allies.
So, you think giving ISIS free speech is constitutional? Everything they
represent is anti-American. Intolerance of Christians, beheading of children
subversion of women decimation of different religious groups and this is
warranted as free speech?
Sorry you hate America. Your opinion is dangerous because you stand for
nothing. A nihlist or a savage Muslim is what you are.
If you believe ISIS warrants free speech then the constitution stands
for nothing.