A non-Muslim friend of mine had a beard that he had let grow without trimming. One day, he trimmed it and I told him it looked classier and cleaner than before. These words imply that it is bad to have the beard he had before.
I'm afraid I've committed shirk, because I believe there are scholars in Islam who say it's obligatory to let your beard grow without trimming it. And I said that having trimmed your beard is better than not trimming it, which is contrary to what Islam says. And I was aware that this is contrary to what Islam says.
I believe that when we deny something from Islam, and we are not ignorant, then we are committing shirk which requires renewing one's faith. Does what I've done fit into this scenario? Do I have to say the shahada again? Is what I did haram?