I agree with Doris Day that you are no longer using CIO to get him to sleep through the night. He's been doing that for months. CIO is really what you did in the beginning for 3 or 5 or 7 nights, whatever it was, to get him to sleep through the night and put himself back to sleep in the middle of the night. So it worked.
That's not what's going on here. He's in a really frustrating and annoying habitual practice of screaming for 20 minutes. You have to figure out if this is "just his way" and something you and others can either live with or hope he grows out of, of you can address it by teaching him to calm himself in bed before falling asleep. I think, at this point, I would try some calming techniques because you really can't have him doing this when he's 2 or 5, right? So you have a great nighttime routine with bath, bottle etc.).
Are you positive that there is nothing about the bottle that is causing him some abdominal distress? Can you give that to him an hour before bed and keep him upright? At 9 months he shouldn't need to be fed right before bed. If you feel he needs the comfort of the sucking, can you water down the formula or give him plain water? Make sure he burps of course and let everything settle.
Otherwise, I would lay him down but put a hand on his head or shoulder or whatever, no talking. Just gently rub/caress until he calms down. You could also try saying the prayers with him lying down so he hears your voice and doesn't associate lying down with you leaving the room. Get him completely calm in a lying down position. Try this for 5 full minutes, 10 if necessary. Next night shorten the time, make it shorter and shorter each time, until it's just a little pat. Over a period of a week or so, hopefully it will resolve.
Do these issues occur when other people put him to sleep? What if his father or a babysitter is the one to put him in bed? I'd make sure everything in consistent.
I agree with you NOT to give him the binky. That's the problem with them - they soothe short term but then they fall out, and the child can't adjust or calm down.
And I agree with you that you should not rock him to sleep - there's always the disruption when you stop and put him in the crib. If he doesn't like the singing, then maybe he just needs pure quiet.