The difference between Lain's path and Haruhi's path demonstrate totally different worldviews.
Lain's worldview is a selfless one, as if there is something greater than her worth sacrificing herself for. This is most closely related to Christianity, as can be assumed from the Christian themes and imagery throughout the show. To lay down oneself not for the greater good, but for something greater than the self, is righteous and admirable. This is why Jesus did not resist the Romans as they captured him, beat him, and crucified him. Selflessness is admirable because it involves doing something to the benefit of other people or other tribes at the detriment of one's self or one's tribe. There is nothing tangible to be gained, yet there is still gain from it. Moral fulfilment is often achieved through selflessness.
On the contrary, Haruhi's worldview is very self-centred. While she may have rejected the role of God, she lives in such a way that everything must revolve around her. She rejected the role of God because she felt appreciated. We can assume that she would have embraced the restart of the universe if she did not feel any appreciation from someone she valued. This worldview ironically lends itself to atheism and the rejection of something greater than reality.
That's a fair addition to this parallel. It's natural that the god takes the selfless approach while the human takes the more selfish approach.
But that isn't to say that the conclusion of the melancholy episodes were suggesting pure selfishness. After that point, the importance of connection the melancholy arc raised was integral for her moments of growth. The baseball episode "The Boredom of Haruhi Suzumiya" involves Haruhi's acceptance of Kyon's wishes to end the baseball game, through mutual understanding after they exchange a smile. "Remote Island Syndrome" has her genuinely concerned about the mystery going on and her desparation upon seeing Kyon unconsciousness was notable. It's true that her selfishness didn't dissapate entirely, as the sigh arc was a thing. But post sigh in particular, it was more pronounced. Her self-consciousness in the concert episode "Live Alive," her playfull attitude in "Someday in the Rain," her accepting Kyon's suggestion of not betting Yuki/Mikuru against the Computer Club and letting Yuki join them are examples. Not to mention in disappearance, non-disappearance haruhi was far less selfish than previously: the scene while the OP was playing when she was getting along with Yuki and Mikuru, her asking everyone about their availability for christmas, her looking over Kyon post the Disappearance, and her desire to perform for a children's chrismas party. Although the appreciation aspect bringing Haruhi out of her escapism is selfish in a way, it was emphasiszing the value in relationships, which overall alleviated her selfishness with time.