How is it that the Holy Spirit dwells within a believer’s spirit?
St. Irenaeus said we receive all the gifts of the Spirit at baptism. Although we cannot utilize any of these (if infancy is when we are baptized). However, the essence of the Holy Spirit is such that he is always with us even at baptism when our cognitive abilities are barely beginning?
What then when an adult, or young child who has reached the level of reasoning, becomes responsible for their actions are they able to understand the presence of the Spirit who dwells within?
One criterion for that is their understanding of right from wrong. The catechesis to these individuals must be taught in some manner since each one is now the person to answer the required questions of belief in the church's creeds. They actually have a better opportunity to answer for themselves since now the choice to be baptized and enter into the church is theirs alone. Unlike when an infant is spoken for at their baptism.
The presence of the Holy Spirit in a believer is not by osmosis or some magic vapor floating in the area and suddenly takes residence like jumping into an empty body. At baptism, the celebrant, priest of deacon, pronounces the words of baptism over the head of the recipient and with the words of (name) I baptize your in the name of the Father, and of the Son, and of the Holy Spirit, Amen. The two requirements, word and action of a sacrament becomes official and the Holy Spirit is now part of the person receiving sacramental grace.
We may hear the televangelists speak of baptism of the Spirit, being the official announcing a person to be saved at their meetings and anyone who seeks Christ to come forth (an altar call) and after a prayer over them they are now a saved Christian.
I believe that the type of coming forth and being baptized without a ceremonial event is not what we teach, but it does bring some people to meet Christ and that is part of evangelizing. The important factor is when we accept the teaching of Jesus and are open to his Spirit becoming one with us is the essential sign of knowing the Holy Spirit lives within each one.
At some point we may have been taught that as soon as we sin, the Spirit leaves us. Not so! That is why when we do sin it hurts the divinity of Christ in such a way that he exerts all his power to bring us back to our senses. There is no human who does not fall from grace. Even proverbs says; “For the just man falls seven times and rises again, but the wicked stumble to ruin.” (Prv 24: 16). The Holy Spirit never leaves us once we accept him through faith.
Jesus reminded his disciples that his Father would send Christ’s advocate to us. “The Advocate, the Holy Spirit that the Father will send in my name - he will teach you everything and remind you of all I told you.” (Jn. 15: 26).
From this explanation, we see that the Holy Spirit enters us through the sacrament of baptism, remains with us constantly, and gains the words of Christ through his Father. This is theological and the truth that the Roman Catholic Church teaches us. CCC 683 - 686.
When Pentecost comes the Spirit is released into the world and brings the continued element of salvation that Christ gave you and me through his crucifixion, and his resurrection and ascension. We are to repeat this very promise, perhaps even with some or a lot of suffering as in carrying our cross if we wish to be his disciples. “Whoever wishes to come after me must deny himself, take up his cross, and follow me. For whoever wishes to save his life will lose it, but whoever loses his life for my sake will find it.” (Mt 16: 24 - 25).
The Holy Spirit dwells within each of his believers whose faith will open his own spirit to the presence of the Holy Spirit.
Ralph B. Hathaway