Nothing Logic about it. Yes you can go make your sign and hang it under your shingle. Its called Freedom. Granted to you as "inalienable rights" by the supreme law of this land.
Go look up the Westboro Baptist church. If you want a lesson on the kind of crap people can freely display. Yeah its a really misguided religious sect making the rest of Religious folks look bad. But the Constitution says they can say what they want, which established precedence, which provides the avenue by which you can too. Regardless of whether or not it offends other folks.