Both Christianity and Paganism are dead because they can't invoke sincere belief anymore and cannot stand up to scrutiny. I think the future of religion will be a blend of Neoplatonism and hero-worship/ancestor worship. Russia's cult of the great patriotic war, for example, is in a way a form of secular ancestor worship.
Natural law would be seen as a manifestation of God's will. Things like Darwinism, phrenology, ethnocentrism, and ecology can thus be conciliated with faith.
Belief in a cosmic mind aka God which can be justified scientifically. Add to that hero worship and ancestor worship. Over time, great heroic figures like ace pilots, or great scientists become saints and then ''Gods''/Archetypes of the warrior and scholar respectively. Cults of valor and knowledge grow around them. Same for beauty, fertility, and loyalty.
Such a religion would have more staying power in the face of science and skepticism due to its emphasis on natural law and a platonic concept of God. It would also be adaptive to societies due to its emphasis on a natural aka biologically adaptive mode of being (High fertility, ethnocentrism, eugenics, etc.)
I for one nominate Eric Hartman and Hermann Black for the archetypes of Hero and lord of war respectively.
And I nominate Kristina Pimenova and Mackenzie Foy as the twin Goddesses of beauty.( ͡° ͜ʖ ͡°)