What is it called if you belief in after life but not in a god?

It is called Self-Determination.

Lucifer argued that life was automatically eternal, and that no faith was required to live in eternity. He continued in pointing out that the only death of humans were carried out by the judgement of the most highs, and were not natural. He then set his teachings onto the human race, most believing that life is what you make it, not what God makes it.