Christ Centered Gamer

Alright so, obviously Booker Dewitt is offered the chance for baptism after the Battle of Wounded Knee. If he takes the baptism, he becomes Comstock, and if he refuses he remains Booker Dewitt who becomes a drunken gambler type. Comstock meets Lutece, and he begins to aid them with their research. When they first jump dimensions, Comstock takes adversely to the jumps, and ages faster and becomes sterile. He wants to have a kid though, so he jumps timelines and goes into a timeline where Booker refused the baptism but had Anna. Because he still feels guilty, Comstock presents the idea of him absolving him for bringing the girl. Hence "Bring us the girl and wipe away the debt" (Not super sure on this part, slight speculation). After he gives Lutece the girl, shown at the end, he becomes even more plagued with guilt, tries to get her back as Comstock leaves into another timestream, cutting Anna's pinky. So in reality, Booker lives alone until the events of Infinite, continues to fail in retrieving Elizabeth, and continues to choose to die at the end, then reliving the events. Hence the part near the start with the coin flipping and why it landed Heads, the allusions to the "Will the circle be unbroken", etc