My thoughts would be … it’s a hard issue, but I do not think the banner and booth at this event is a good idea. I can guarantee they will see the banner, roll their eyes and complain about it and move on. It may make them believe that they are not welcome in the Church. I don’t think it would make them think deeper on the issue. Maybe host a talk on a separate day about how the church views homosexuality, chastity and theology of the body and all of those things and if any members of the gay community want to hear what you have to say they can come out to it. Like some other posters said, you can’t convey all of Catholic teaching on this issue in the form of a banner. This issue is deep and requires a thorough explanation and a banner cannot go into depth. I guess I just don’t think this event is the right place for it. And this is likely an irrational thought but if you hang something on your church, you may risk people vandalizing the church or something - I dont think the majority of people would do something like that, but you never know if there is one angry person there who would.