Living in the flesh without Christ is natural. Unfortunately, natural is selfishness. We were born in sin. We don’t have to teach children to say, ‘mine’ but rather to share.
Life is backwards when it’s all about self. I hate to be the bearer of bad news but you should already know it’s a fallen corrupt world. That’s why we need to be reborn in the Spirit. See John 3:1-16.
It’s wise to supernaturally subdue the flesh to make more room for the Spirit.
Check our Romans chapters 6-8. Deep stuff to ponder. Positionally all believers are pure, physically we remain in a battle whether you realize it or not. As important as that is, the real battle, the ultimate battle is of spirit. Lord help us.