Thomas Hobbes's method and aims in civil philosophy in general, and in Leviathan in particular, lead him to leave the "seeds of religion" out of the War Argument because to include those seeds of religion would be counter-productive to his method and aims.
Hobbes's method is based on science, logic, reason, materialism, and empirical observation, none of which is useful in analyzing God or religion. For Hobbes to include the intangibles and mysteries of religion and God in his rational analysis of human nature and politics would have been to poison the entire project with uncertainty.
Hobbes's aim is to construct a philosophy, built on what he hopes are the air-tight bricks of reason and mathematical logic, which convinces human beings that they should immediately form a state in which they give their rights and their lives over to an all-powerful Leviathan forevermore in order that they may be protected from the return of the state of nature and the constant war of that state. For Hobbes to throw religion and God into the very beginning of the project would have led to the very problems he was trying to avoid by conjuring the project in the first place. After all, Hobbes in writing Leviathan was trying to show how peace could be won only when all citizens in a society had given up their rights to the Sovereign, who was himself a god of sorts, certainly a more tangible deity than the God of religions. By introducing God or religion into the recipe, Hobbes would have effectively posited an opposing God to his Sovereign. At the very least, he would have opened up endless theological debate as citizens divided up along lines of religious dogma and factionalism. These divisions were precisely what Hobbes was trying to avoid in designing his ideal state from the bottom up, that is, from the dissolved state, the state of nature and constant war, up to the Leviathan-run state of obedience and order and peace.
As Gregory S. Kavk...