As I said earlier
here &
here and as
inkaneer just said now, to receive the free gift of salvation, Catholics must until their last breath, maintain the righteousness that they received during the Sacrament of Baptism. Ongoing righteousness is maintained through the reception of the Sacraments of Confession and the Holy Eucharist. While belonging to the invisible Body of Christ, Catholics recognize that they absolutely need the Sacraments of the visible Body of Christ, the Catholic Church, as their assurance of righteousness and salvation. Hence, believers require the Catholic Church as the “fullness of the means of salvation.”
In the case of non-Catholic Christians, while through faith in Jesus and the Sacrament of Baptism, they are admitted into the invisible Body of Christ as their first instalment towards salvation,
once they have committed mortal sins, they possess NO means of reinstating the righteousness that they had originally received during the Sacrament of Baptism. Such a status holds serious consequences, the unrighteous sinners being unable to enter the Kingdom of Heaven.
Within the Catechism of the Catholic Church, it states, “If (mortal sin) is not redeemed by repentance and God’s forgiveness, it causes exclusion from Christ’s kingdom and the eternal death of hell, for our freedom has the power to make choices for ever, with no turning back.” (C.C.C. # 1861)
What are these mortal sins that can impede one’s entry into the Kingdom of God? In the Letter to the Galatians, we read, “Now the works of the flesh are plain: fornication, impurity, licentiousness, idolatry, sorcery, enmity, strife, jealousy, anger, selfishness, dissension, factions, envy, drunkenness, carousing, and the like. I warn you, as I warned you before, that those who do such things shall not inherit the Kingdom of God.” (Gal. 5:19-10; C.C.C. # 1852).