I need to compile a list of where non-Christians are allowed to post because I'm not sure I know them all myself. I check the SOP too if I'm not sure.
Most of the time I see them posting in Ethics & Morality, Struggles by Non-Christians, and Christianity and World Religion. Respectful posts are sometimes made in other sections too. For example in The Ancient Way (the EO forum), a non-Christian can post in fellowship or asking questions and be welcomed. The restriction there is that only Orthodox teaching is allowed, so you couldn't get a perspective from Catholics or Protestants if it were different. But if you ever have questions about posting and rules, feel free to pm me and I'll be glad to help if I can. If I don't know the answer, I will find out for you.
God IS Spirit ... prior to the Incarnation of Christ, all of the Persons of the Holy Trinity were only Spirit. It was not until Christ came to be born of the Virgin Mary, taking on human flesh from her as any child does from its mother, that God had a body in any form. Because He has united Himself with humanity, being both God and man at that point, and remains so, the material world is now united to God in that sense. (Making the way for mankind to be elevated into communion with God - though NEVER becoming God in Essence - but this is how we will eventually be restored and all creation along with us.)
Before man was created, there was always God, Who is Spirit. He also created angels, who are spirit beings. Man was the first creature who was given both that spirit from God AND a physical body. There is something distinct about our spirits compared to that of animals. It is a higher form, such as the spirits of angels are higher, and represents a connection between us and God (as it does for the angels). Or at least the opportunity for connection, since some of the angels willfully separated themselves and since we also have that choice if we wish it.
I'm not sure if that is answering your question? But the way in which God gives that spirit to man is unique, from animals. However, it is not the same thing as "having the Holy Spirit". Before Christ the Holy Spirit would unite temporarily with a person (often a person was a prophet as a result) so that He could carry out a necessary work through that person. It could be a brief union or a fairly longer one from a human point of view. But since Christ having come and ascended, and the descent of the Holy Spirit at Pentecost, the dynamic has changed and God now unites Himself with those who receive Him, never to abandon us (though I believe we can purposely drive Him away from us if we were to choose ... but that would be apostasy).
At the same time, it is also true that God sustains (and always has) all of creation by His energies, and as such He is the ultimate source of all life. But again, this represents a different level of involvement from His other activities.
I'm not sure if some more modern Christians would agree, and perhaps Catholics don't have quite the same understanding either, but we Orthodox understand God to exist in His Essence (his "God-ness" - His Being, which we can never know) and His Energies, which are the way He acts in the world, the way we can interact with and know Him. What we call "grace" is His energies working. And we would say that our experience of grace IS the Holy Spirit. Yet it is important not to think of Him as some kind of impersonal force, like electrical power or something. He is a Person, with thoughts, a will, and the ability to interact with us.
My thoughts were a bit scattered, and I'm not sure this can be assembled into a coherent understanding that helps or not. We can know God in a way, but in another sense God is past our ability to figure out. So He is difficult to explain in words or concepts. I hope it could be of some help at least.
