Rapture completely blew my mind, I wasn't expecting it at all. And to tie it into the storylines (at least, tangentially) was a stroke of genius.
Did anyone catch the Little Sister trying to wake the Big Daddy just after Songbird dies?

Here's a comparison of Rapture in BS1 and Infinite btw: https://imgur.com/a/gllDv

I had a friend (Who was lukewarm on the game) post this on his facebook.

Here is a video breakdown of the ending of Bioshock Infinite.

http://www.youtube.com/watch?v=y3FRSMiRVAs

So much is explained, but is it ever explained where the fuck Elizabeth gets her 'tearing' ability from?

Why do a seamingly smart group of people who built a floating city, worship politicians like they are gods?

Why do soldiers of a floating city use guns instead of just drinking the numerous bottles laying on the ground that lets them shoot lightning?

I remember seeing a map of where Columbia floats, and it's always over land. Who the hell is the poor guy who has to clean up all those warships me and Songbird took down?

1. It's very heavily implied that Elizabeth's tearing ability comes from her pinky being cut off and left behind when she's taken by Comstock.  She's effectively in two places at once.

2. The Lutece's don't worship Comstock or any of the founding fathers; only the people do because Comstock uses the tears for his "prophecies" and, hell, they don't know any better.

3. Because shooting lightning really only stuns your enemy for a few seconds.

1) What Motsy said.  It's kind of a dumb answer but there you go.  Pan-dimensional travel is weird.
2) The people of Columbia didn't build Columbia.  Comstock and the Luteces (probably just Ros), and probably Fink?, built Columbia.  And frankly, given their jingoistic/extremist nature I'd be willing to say the people of Columbia aren't necessarily enlightened, maybe even not smart.  And, again like Mots says, the people don't know what the tears are, and they don't know how Comstock is using them, and I'm willing to bet Comstock's "prophecies" have mostly been accurate.
3) Because Gameplay.  Or because they're terrified of the side effects, which, given the animation that plays when you get a new one, is probably a pretty valid fear.  Or because they have giant robot presidents to back them up.
4) https://www.youtube.com/watch?v=9tMjyGJdzwk Don't know!  But in this vid, it talks about a chunk of the city being discovered in the Alps.

The video brings up an interesting point about Dewitt/Comstock that made me realize... honestly... It might have worked out better of post-baptistm Dewitt was simply involved in the genesis of Colombia, as opposed to being Comstock himself--like, say, Comstock was his partner or something, and post-baptism-Dewitt was a seperate character, maybe even a villain you encounter, or something--then the ending would mesh a lot better.  Like if Dewitt drowned before getting baptised then Comstock wouldn't have the get-up-and-go on his own to create Columbia, thereby ending the cycle.

Or maybe if Comstock wasn't such a radically different character or the YOU ARE COMSTOCK reveal wasn't so sudden and random feeling.

So sure..I'm completely clueless about how baptisms work so I'll concede the fact that 'most' name changes resulting from religious revelation and a baptism may follow a certain formula or pattern...but does that necessarily mean that ALL baptismal name changes have to conform? I think it's fairly nitpicky to say that it's IMPOSSIBLE for a man named Booker DeWitt to undergo a baptism and change his name to something completely different.

There was another point the video made about how it's unrealistic and unbelievable for a man who's basically a religious fanatic and NOT a captain of industry to gain the money and put together enough funds to power the project necessary to build a floating city. The video also talks about how it's goofy that a foreign scientist, Rosalind Lutece, would pick Comstock, of ALL people to bring forth her vision of a floating city.

To that, I just think about the basic premise of the game, of multiple universes and infinite realities.

I think there are just as many realities out there were Comstock COULDN'T get his Columbia project off the ground. Just as there are probably realities out there where Lutece didn't end up choosing to help Comstock.

But in those realities, the game and the things that happen in the game wouldn't have existed so we don't visit/play through those realities. I think Infinite essentially deals with the one in a million chance that everything goes exactly wrong and creates this whole...situation. The leak across the multiverses that needs to be sewn back together.

Like, sure, it's likely more realistic that Comstock doesn't succeed in building Columbia and that Lutece doesn't come to him to offer her assistance and any number of other variables that could occur that would lead to Columbia not being built.

But I think of the game as showing us that one off chance that everything goes just right and Columbia happens and Elizabeth gets kidnapped that sets the cascade into motion. Thinking of it that way...that the game is set in the one series of realities where everything lines up just so...it doesn't seem that far a stretch to me.

There was also that last, kind of pithy point, about why interrupt the baptism at the end when  you could have just as easily gone back to any point before the battle at WOunded Knee and prevent Booker from taking part, thereby removing the possibility of the baptism and Comstock?

The way I saw it, it was kind of the only way to really be sure.

I saw it as the moment of conception and the moment of birth.

If you went back in time to prevent your own existence...you COULD go back to the night your parents had sex that led to you...OR you can go back to the moment you were born and kill the baby then. To me, I saw the difference as eliminating a chance of you being born compared to making sure.

That's a good way to think about it, actually, and framing it in that kind of context helps the other bits fall into place.  The circumstances leading up to Columbia's creation are weird and unlikely, but if you accept the infinite world theory then you also accept that somewhere out there are all the worlds where weird and unlikely things have happened.

I think a lot of people are taking the drowning of Dewitt a little too literally.  The game never really fleshes it out, but when I was watching it I was seeing the drowning as a more of an active-but-symbolic thing.

Like... there's not this preacher out in this river about to baptise this guy, and then suddenly a bunch of cute brunettes show up and drown the baptisee.  The way I see it--Elizabeth, all the active versions of Elizabeth, including our own, are coming together to wipe out the timelines themselves, via their quantum abilities.  They're snuffing them all out of existance and wiping the slate clean, not by physically drowning a man and altering history, but by altering the history directly so that he always drowns/will drown/drowned (I love time travel verbs).

And then moving on past the credits, looking at the events linearly the Dewitts who would even in in the water to drown would be the ones who chose to be babtised--ie, the future Comstocks--and the ones who went part way into the water, changed their minds about getting baptised, then slipped and hit their head on a rock and drowned.  So my/our/your Dewitt, the one who would go to Columbia to free Elizabeth if Columbia existed, goes on to retreat to New York and drink himself into a stupor and have Anna.  But with no Comstocks surviving the baptism (which is an awesome band name) there's no one trying to buy the baby from him.

And now some personal interpretation from a chronic optimist:

The Dewitt past the credits, that's my/our/your Dewitt.  And the baby--and there is a baby, says the optimist--is Anna, who will never be Elizabeth, because Elizabeth no longer exists or at the very least she exists in the same timeless, worldless way Ros/Rob Lutece do, scattered. 

And here's the telling thing.  My/our/your Dewitt hears the baby, mobile? and goes to check it out, and asks, "Anna, is that you?"  Which is a sort of curious way to speak to your daughter, your only daughter.  Who else would it be?  Unless... My/our/your Dewitt has retained, somewhere deep down, some memory of the game's events, memory of multiple versions of the same woman who is his daughter with another name.  And from the point of the last figurative curtain fall onwards, the inner optimist in me has a head!canon in which Booker Dewitt gets his shit together and raises his daughter.

So did anyone take the time to look at Booker's Office after the credits? I honestly just went straight for the door, not even looking to see if the Wounded Knee or Pinkerton Badge, etc. were still there or if anything had changed. 

I think the guy is getting to hung up on the religion thing. I think Lord Snow gives the best counter, but when it comes to baptismal names, take into account Comstock's religion praises the Founders, not God. 

Zacharay, Hale, and Comstock are all names found in American History (Zachary Taylor, Nathan Hale, Anthony Comstock - Comstock Laws, all names found before the time of Wounded Knee) so maybe that's why it was chosen. 

The baptism, I see as going two ways, with DeWitt becoming a "new man" in both. DeWitt was ashamed of his actions but refused the baptism and spent his life dealing with them as an alcoholic and Pinkerton whereas Comstock found religion to become a new man, but it was his new religion where instead of being ashamed of his actions he embraced them instead and became ultra nationalistic to justify them.