If you don’t believe Pope Leo XIII, how about John Paul II?
He makes is clear that only the just have the gift of the Holy Spirit dwelling in them.
He writes:
“We can say that, on the basis of a Christian life characterized by interiority, prayer and union with God, there is a truth which like all theology and pneumatological catechesis derives from the texts of Sacred Scripture and especially from the words of Christ and the apostles: that of the indwelling of the Holy Spirit as a divine guest in the souls of the just.”
He goes on and says: “Of course, the Holy Spirit is present and at work in the whole Church, as we have seen in preceding catecheses. But the concrete fulfillment of his presence and action comes about in relationship with the human person, with the soul of the just person in whom he establishes his dwelling and pours out the gift which Christ obtained through the redemption.”
I don’t disbelieve either of of these Holy Fathers, merely understanding them properly. Pope Leo alludes to the Holy Spirit’s presence through the “traces of divine power and wisdom appear even in the wicked man”. Pope John Paul is writing about the sanctifying presence of the Holy Spirit, not denying His presence by power. These are two different ways in which He is present: sustaining in existence and sanctifying the soul brought by grace from servanthood as a creature to sonship as a new creation in Christ.
It is absolutely true that God sustains all of creation, even those who do not believe He exists. But He does not dwell in every soul…just the soul of the just…None of my professors in seminary would agree with anyone who says that the Holy Spirit dwells in a soul who is in mortal sin.
God sustains all of creation by His Presence in all creation while not being a part of that creation. Your professors would surely know of His Omnipresence since it is
de fide that He is everywhere present in created space.
*Where shall I go to escape your spirit?
Where shall I flee from your presence?
If I scale the heavens you are there,
if I lie flat in Sheol, there you are. Psalm 139:7-8
Am I a God when near, Yahweh demands
and not a God when far away?
Can anyone hide somewhere secret without my seeing him? Yahweh demands.
Do I not fill heaven and earth? Jer. 24:3-24. *
I posted this from Ott’s Fundamentals Fundamentals of Catholic Dogma wherein he addresses the principle:
“Since the time of [Peter Lombard] theologians more closely determine the omnipresence of God as a presence according to power (per potentiam-dynamic presence), according to knowledge (per praesentiam sive scientiam-ideal presence), and according to essence (per essentiam-essential or substantial presenc). Through this essence He is present substantially in all things, including the created spiritual essences (angels, demons, human souls), as the immediate origin of their existence.”
“. . .in addition to this general, natural, presence of God, there is also a special supernatural presence or indwelling of God, by the supernatural efficacy of His grace, in the soul of the just man (John 12:23; 1 Cor. 3:16; 6:10). . .”
This last part speaking of the “supernatural efficacy of His grace” is what John Paul is addressing in your quote.
If He is present (all three Divine Persons present “where” One Is) substantially in the demons, He is thus present in souls in mortal sin.