Because it seems to me that people only start to consider themselves as "Being of the Spirit" AFTER their worldly "treasure" has 'solidified to them.' To illustrate what I'm talking about: marriage. Marriage seems to be one of the most worldly things, and yet its sanctity is something that 'religion' (the very source of 'being IN the world, but not OF the world') uses to justify "descending back into Jungle Law." 'Marriage'--in terms of law--makes you "OF the world." (Now, I don't want to encourage divorce with that statement ... revealing what the true purpose of marriage is (other than the 'raising the children right'-reason & the 'satisfying the parents that they've raised their children well'-reason): taming the 'Jungle'-instincts (beside the hormones, there's "the lion-like NEED to know your respected place in the pack"). That works well for 'normal people,' but I am not given my 'place in the pack' due to my loss of the ability to 'work well with others'---the attitude arising from some minor quirks of my past ... call it PTSD, the trauma being my several minutes of death experienced due to the stupidity of an automobile-operator. If Christians today were "in the world but not of the world," I would have the place of a 'justified adultery-gigolo'---free to love my friends' wives freely. That would 'cool my raging Jungle-hormones.' Right?