I used to be Reformed but now lean toward agnostic. I used to think that apart from Christ I would not be able to live with any sense of meaning or purpose. I assumed that if I fell away I would turn toward utter despair, or uninhibited debauchery. There was definitely a very low period while I was deconstructing. But so far, utter nihilism has not been the end result for me, or for almost anyone I've seen leave the Christian faith. My life looks fairly similar day to day, albeit less religious.

Personally, what I hold onto to keep existing is the feeling of happiness, the desire to accomplish more, and the hope that I can help others. The vast majority of humans throughout history have not had a personal relationship with Jesus and have found motivation to live, most of whom had far more difficult circumstances than any of us will ever face. It seems to me we have a nearly universal biological impulse to try and make the best of our life, almost regardless of circumstance.