So in the beginning of 9X05 we have Abuela and tia pepa talking to Eddie because they found the pray book and rosary. Eddie explains the pray book was Bobby's and the rosary is his. I think that's important in the context of the scene after the exorcism call and the rest of the episode. The episode as a whole is watching both buck and eddie process their grief for Bobby through how the each connected with him. For Buck that is baking and for Eddie that is religion. We see that most notably in season 7 where Eddie's reservoir of Catholic guilt is brought up in response to Eddie finding out his ex-gf was a almost a nun. Buck suggest he talks to Bobby about as someone who is a practicing Catholic. Then later Bobby gives Eddie the prayer book and it become a symbol of Bobby now that he is gone. So in the way the audience sees Eddie and Eddie's connection to faith is more symbolic in the rosary. Yes, Eddie goes to Abuela to mass but he says "i did it for you, because you are my Abuela and I love you" Once again this not really about Eddie and his faith or belief in God but rather he is doing this for his "family." Then there is the exorcism call and the audience sees how much this impacts Eddie as he gets snarky with the priest and he calls out the parents. It cuts to Eddie staring at the pray book (Bobby's pray book), the rosary is not there. It is Eddie look at Bobby, he admits to his tia and Abuela he doesn't know if he is going back to mass for Bobby (pray book) or himself (rosary). So, after a call the rocked the hell out of his already shaky faith in God, the audience sees Eddie staring at just the pray book, like he is still looking for Bobby but he does not believe he will find it a church. This is then cemented in the disagreement he has with Buck. "God wasn't in that church, and Bobby isn't in your house." In the end Eddie learns how he can connect with the ones he lost, at the ofrenda with Chris, he is reminded that they are always in their hearts. Much like what Abuela said to him outside mass.
This post kind of got away from me but my point was the symbolism of Eddie's faith in this episode was the rosary and we only see it at the beginning of the episode, every other time we see a reference to faith or religion it is Eddie doing it for others or denouncing it. Eddie learned how to process his grief in away that was his own much like Buck. Thank you for coming to my Ted talk.