Depends on how specific you get and whether your audience agree with you as to whether a specific activity is sinful or not. If Person A believed Activity X isn't a sin, then an evangelist banging on about how Activity X is sinful and those who commit it are Hell-bound spawn of Satan isn't exactly going to win hearts and minds, short of course of a miracle to conversion by the Holy Spirit. For example, a Baptist Minister of my acquaintance stands in the tradition of Baptist pacifism in Wales. He believes that gun ownership is a sin. If however he uses that as a focus of his Gospel message at, say, an NRA convention or indeed many places in the rural US, I don't think he's going to get many conversions...