G.L Lambert responded.
The main thing that sticks out is "that card has been a point of interest before". Which means that it has been in his room for some time and you aren't the first girl to react to it this way. Maybe it's sentimental, maybe it's a power play to get a reaction out of women that enter his room or to keep them on their toes. Regardless of his true motive, I think he feels guilty for playing that game in the first place. I'm assume the first or last girl before you that saw that card probably bought it up to his face, you didn't bring it up you snooped then called him out on your theory. I think you triggered that guilt because maybe he is holding on alternatively if it is just for "color" then you push the button that it's a stupid thing to have in your room once you have a girlfriend. The point being, this is a fresh relationship, you guys are still virtual strangers, and for some men it's hard to mature out of ******** like old cards in the room as reaction starters.
I don't think you were cold via text about the sermon, it wasn't a vibe, he was projecting because of his shame. It's not about the card, it's about him not knowing how to be a boyfriend or at least being humbled by the new rules that comes with being someone's man. No one teaches guys these things, that they don't yank on the emotions of girls they like or push the buttons of women they commit to like they do girls they are simply dating or sleeping with. His distance is all about guilt and shame because he doesn't want to admit that it was foolish to have it there in the first place.
The only conversation you can have to get past this is to make it no longer about the card but about empathy. This is what should be said, "Don't think I'm upset about the card itself or that it's jealousy or suspicion. This is a new experience for the both of us and I think it's important to be transparent more than usual because we don't actually know each other to the point of trust. Put yourself in my shoes, how could you not react to that image with questions? I buy your reason, but now that we're together I would hope you would either remove something like that or tell me with full honesty the story behind it before I see something like that which can't help but cause suspicion. I don't want to come off as jealous, so I'll be sure to ask and not assume, but we both have to be open about communicating, not about a stupid card, but anything that raises mystery." Now you can put that in your words and break it down, but the message is to make this about what you expect as a girlfriend, because clearly he doesn't know what the rules are if he's holding on to old cards even after it's come up before.