I would bet that nobody said yer pop’s attending the Cruz talk was a “sin” (‘sin’ seems a front-loaded word co-opted by evangelicals), probably they said it was ‘ill-advised’ or some such.
Here’s why it’s ill-advised: Your dad, like it or not, is not one of the anonymous hordes. He is a name brand. He is Mr. Holland of the Opus. He is the Hello in Goodbye Girl. When he shows up, people notice. They make a big deal about it.
So, it’s tedious, but he has to consider this when he shows up at a political rally. Whichever candidate will exploit his presence as proof of support. Fortunately there is plenty of research he can do, even circumventing the usual media. There is youtube. There is lots of youtube. For instance, this:
So but I think it’s right noble of you to stick up for the old man. I was like that once too, thought my dad was the cat’s pajamas so whatever he did was okay by me, but then one day I noticed that he was not laughing AT Archie Bunker, he was laughing WITH him. Big difference. And then I decided I don’t have to agree and I became an adult in that moment.