What happens to consciousness when we die?
I was thinking more along the lines of the separation of this world or της κόσμος from the kingdom of heaven as depicted by St. Paul, or the difference between the City of God and the City of Men as described by St. Augustine. The Christian point of view tends toward seeing present choices in this life as directly involved in immortality as the desired outcome.
But, as a professor I had long ago pointed out, the text says "eternal life" not life after death. Not tasting death only makes sense as a way of life. Nobody can prove the future. Accepting that certain conditions apply is either a discovery or an assumption. Our results will vary. The anticipation is the central focus.
All of that is a different matter from trying to understand consciousness as a phenomenon or phenomena. But the problem does not come from being stuck in one worldview or another. We might need some more philosophy. Spinoza noted that we use frames of reference that a Creator would not.
As for the Nietzsche mention, I was interested in the idea of him being motivated to find the opposite pole of Christianity. He employed a certain version of Eternity to collapse the Two World idea.