All of the above?

A) The bible-thumping has been Tebow's saving grace, as it seems to keep him relevant to a certain demographic who will cheer him on despite clear evidence that their god has forsaken him. That crowd likes to buy Tebow jerseys whether he's a winner or not.
B) It's interesting you mention the Heisman. A lot collegiate big fish find themselves out of their depth in the NFL. Tebow's a strong rushing QB with a relatively poor arm, and NFL defenses tend to gobble guys like him up, since they don't need to pay as much attention to the passing threat.
C) I don't think so many teams hate him, and apparently he isn't really locker room poison either. He isn't really a dick, he's just prone to godding up press rooms and twitter feeds.
D) I think the reason he's been finally cut is mostly B, he's just not that good, though that's somewhat unfair to say. Tebow is a stud athlete but he isn't such a great passer, and his decisions under pressure are often costly to his own team.

Of course one could say he's relatively inexperienced, but he hasn't really fit into three different systems now, and it would take a real leap of faith to build a system around a guy who's such a poor passer. Certainly not something The Hoodie is going to do up in Foxboro.

Which actually may bring us to a good question, that is, what was Bill Belichick doing giving him a chance in New England? I have a couple of ideas about that. One is that Belichick has a protégé in Tebow's former coach at the University of Florida, Urban Meyer, and there was some kind of personal favor being handed out. The other is that Belichick wanted to try Tebow at QB in order to show him that he's not an NFL-caliber QB, and possibly use him in another position, or in special situations, because the truth of it is, Tebow is still a stud athlete and could be a real threat if he could learn to catch. A tight end, maybe? Shit, you could line him up to hold place kicks and then have a real threat for the fake kick, who can run and pass better than most placeholders. Of course a roster spot costs money, and it seems like a waste of resources for what would be a rarely used commodity.

But all that is speculation, some of it pretty wild. I think it's most likely that he's just one of many incredible athletic performers who just for some reason or another either don't get the right chance at the right time, or don't make the most of the chances they're given, and wash out of the NFL. It just happens that in Tebow's case, the wearing-Christ-on-his-sleeve bit got him more attention while he did it (and, privilege being what it is, may have gotten him more chances than he deserved).

Thank you so much Hugh, for this explanation. As a New Englander, I've been a bit puzzled by this whole thing, and you explain it perfectly.

I will agree with Hugh; it's mostly that he's not very good in that way a fantastic athlete can be- I'm sure he could run circles around us, but he's out of his league in the NFL, so now he's out of the league!

one of many incredible athletic performers who ... don't get the right chance at the right time

Strongly suggests that Tebow's failure is an Act of God.

I've heard Bill Belichick called many things but that takes the cake.

That makes a lot of sense, Hugh. I wasn't aware of the Belichick/Meyer connection.

Speaking of wild speculation, and athletic talent completely aside, my personal hunch has always been that he is [closeted/in severe denial of being] gay. The gaydar gets twitches from Urban Meyer, also.

That said, I don't sense that most of the NFL gives a shit whether their brethren are gay or not. They just want to play.

The thought of a gay Tim Tebow kind of makes me wish I was gay, so that my occasional fantasies of cuddling with him might seem more reasonable. His is a transcendent hunkiness. I don't really know why, but sometimes I just want to rest my head on that incredible chest and sigh....

Also, regarding the reasons for New England wanting him around, albeit briefly, this ESPN blog post suggests that regardless of the quality of his play, Tebow's training and presence during the preseason had a positive effect, helping to calm and focus the Patriots after a tumultuous offseason. I'd buy that as one of many possible factors.

There are still other possibilities. For example, he might just shuffle off to Buffalo.