Sol Invictus,
This is a serious misunderstanding on your part. The Holy Spirit does NOT dwell in a person who is in a state of mortal sin. This is the crux of Catholic doctrine on grace.
When we are baptized, we receive sanctifying grace in our soul. Our soul becomes a dwelling place for the Holy Spirit.
HOWEVER, when we commit a mortal sin, that grace leaves our soul. God can never be in the presence of sin. This is why we must confess all mortal sin. When we are truly sorry for our sin, and we confess it, we are forgiven! And sanctifying grace comes into our soul once again.
This is why we should not receive the Eucharist while in a state of mortal sin. We are receiving the Body and Blood of Christ, and to receive Him while in a state of mortal sin is sacrilege.
On the other hand, to receive the Eucharist worthily is to strengthen that grace that is already present within us and puts us in communion with God. As He becomes a part of us, we become transformed to become more like Him.
Sol Invictus, remember that God is nothing but love and goodness, and all that He created is good. That includes the human body. We may sin with our body at times, but the body itself is a beautiful creation and is remarkable in all that it can do: our five senses, our beating heart, our blood, nerves, and organs…how do they do what they do??? The way a body can move and balance, from dancing to gymnastics to running to stretching, it’s all so amazing. We think and have emotions. All these things and more are a testament to the power, beauty, and goodness of God.