>>18021400theologians been tackling these problems for over 2000 years, it's safe to say all the possible interpretations were studied in one form or the other. God being in everyone is a heresy dating back somewhere to 3-5th century. Holy Spirit is one of the aspects of God, something external, guiding your actions, through dreams, intuitions. it's like wind in a field, you can see it's influence, but it's not the same thing as your soul.
according to the current doctrine, the state of grace is something that's given to you from the outside. not something inherent to people.
personally, i don't know, i think living it all through your experience is more important than solving intellectual puzzles.