The catechism of the Church states that there are sacraments for the living and sacraments for the dead. There are only three sacraments for the dead, Baptism, Penance and Unction/Anointing of the Sick. Confirmation, Holy Communion, Holy Orders and Holy Matrimony are for the living.
What does that mean?
It refers to the soul/person being either dead or alive in Christ. Prior to baptism and the restoration of sanctifying grace (the real presence of the Holy Spirit in a person’s soul which leaves an “indelible mark, even after the Holy Spirit is pushed out by the free choice of the sinner due to mortal sin) the soul/person is “dead” and incapable on their own merits of receiving eternal salvation in heaven only eternal damnation in hell—they are dead to Christ and eternal life in heaven.
Baptism by the merits of Jesus Christ alone, makes us alive in Him and the door is flung open for us to enter into heaven through the forgiveness of original and actual sins which Jesus alone accomplishes in the Sacrament of Holy Baptism which he has instituted. He alone restores sanctifying grace to our souls, necessary for salvation.
Being alive in Christ we are allowed then to receive the Sacraments of the living, Confirmation/Holy Eucharist/Holy Orders/Holy Matrimony.
If though, through mortal sinfulness, we return to the “death” of sanctifying grace in our souls after Holy Baptism, we must by God’s grace avail ourselves to the other Sacrament of Forgiveness for sins committed after Baptism, the Sacrament of Penance and in cases of extreme illness and nearness of death, the Anointing of the Sick. These sacraments restore the Baptismal gifts of sanctifying grace of Jesus Christ to the soul/person. These sacraments are for those dead to Christ due to mortal sin.
But the question remains, what is mortal sin? Serious matter, knowledge that is it a sin and seriously so and full consent of the will and usually with forethought and planning. If any one of these is lacking, the sin is not mortal or death inducing to the Sanctifying Grace in the soul (the life of the Holy Spirit) so necessary for our salvation. The sin remains a venial sin easily forgiven through an act of contrition, going to Mass or even receiving Holy Communion which is a medicine for sinners not a reward for saints.
In other words, mortal sin that is mortal sin for the sinner is exactly that “mortal” pushing out, by free will, the life of the Holy Spirit (sanctifying Grace) in the soul/person who commits it.
Often in confession, I hear people confessing serious matter, which for them, due to all three criteria for what mortal sin not being present, confessing something they think is a mortal sin but really isn’t. Certainly they are free to confess venial sins and the Church encourages it, but it isn’t necessary to do so.
Thus the question for President Biden’s confessor is, is his enablement of abortion and all its vile forms, a mortal sin for him because all three criteria for what a mortal sin are present or is something lacking in his commission of a “mortal sin” or the mortal sin of “omission” in a serious matter that reduces the sin to a venial sin only?