Locke ends up at St. Sebastian's, Jack angered by mention of Christian

Locke wakes up in Saint Sebastian's Hospital with Jack sitting next to his bed. Jack immediately asks Locke what he is doing there. Locke was taken to Jack's hospital after his car crash. Locke tells Jack "We have to go back" and Jack, who has obviously been drinking plays it off briefly and then gets angry. Locke tells Jack that someone was trying to kill him because they don't want him to succeed. Jack asks Locke if he has ever considered that the idea that he's special is just a delusion. Jack continues saying "Maybe you are just a lonely old man." As Jack gets up to leave, Locke says "Your father says hello" which stops him in his tracks. Locke tells him how Christian told him to move the island and bring everyone back. This gets to Jack whose eyes get watery as he says "My father is dead." Locke replies "Well, he didn't look dead to me." Locke tells Jack again that he has to come back and that he is only person who can convince the others to come back too. Jack gets angrier saying that they were never important and to leave and the others alone. As Jack storms out, it is clear that Locke is distraught.

This was another classic science vs. faith stand-off between Jack and Locke. The mention of Christian Shephard clearly gets to Jack because at this point he started growing the beard meaning that he has already been seeing Christian (screens here and here from "Something Nice Back Home"). Jack has also seems to have starting drinking and/or taking pills at this point because he slurs his speech at one point.