I totally missed that aspect. I didn't notice anything when the canary landed on the picture of Jesus, because it's pretty common to see pictures of Jesus. Nor did I notice anything about the shadow.
Now you've got me to watch it again. Good insight! Wow.

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Yes, Birdy is portrayed as a Christ figure.
I hadn't noticed the bird landing on the Jesus painting, that's another good clue. But I did see Birdy being "crucified" on the shadow on the floor of his cell.
In addition to that, when he pries the canary from the mouth of the cat, it surely appears dead. But he "lays hands" on it while caressing it, and it miraculously springs back to full life, flying around the room.
I think the time from his helicopter crash, through when he is imprisoned in the mental ward, and finally his escape represents the time Jesus spent in Hell.
When Birdy at last leaps off the roof, we all are lead to believe he will die. The next shot of him standing on the slightly lower roof is played for comic effect, but it could also symbolize his return to life. He did die when he leapt of the roof. And then he was risen.
Anyway, I'm not that religious, so there might be other references that escaped me.

i'm sure his positioning on the floor of hte cell is deliberate. long shot, but it also occured to me that when he rescued the canary from the cat, he could have brought it back to life. it did look dead.