I have already told you twice what constitutes a Mortal Sin. But to be more complete: from the Catechism of the Catholic Church:
1857 For a sin to be mortal, three conditions must together be met: "Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent."Catholics are taught to distinguish between Mortal Sin and Venial Sin and there have been many books which discuss it. But if you do not want to study them then what can I say?1858 Grave matter is specified by the Ten Commandments, corresponding to the answer of Jesus to the rich young man: "Do not kill, Do not commit adultery, Do not steal, Do not bear false witness, Do not defraud, Honor your father and your mother." The gravity of sins is more or less great: murder is graver than theft. One must also take into account who is wronged: violence against parents is in itself graver than violence against a stranger.
1859 Mortal sin requires full knowledge and complete consent. It presupposes knowledge of the sinful character of the act, of its opposition to God's law. It also implies a consent sufficiently deliberate to be a personal choice. Feigned ignorance and hardness of heart do not diminish, but rather increase, the voluntary character of a sin.
23For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord. Romans 6:23 NASB
I've 'studied' the text book that Rome has prepared for it's students.
I'v e not yet found the lesson taught in 1857 - 1859.
I have; however; found THIS in the Book:
Romans 3:23 for all have sinned and fall short of the glory of God,
Rome teaches this is NOT true; for it claims that the woman who bore Christ was SINLESS; while she; herself; made sin offerings.
Romans 5:12 Douay-Rheims Bible
Wherefore as by one man sin entered into this world, and by sin death; and so death passed upon all men, in whom all have sinned.
Except Mary...
James 2:10 Douay-Rheims Bible
And whosoever shall keep the whole law, but offend in one point, is become guilty of all.