In order for a sin to be mortal, it must meet three conditions:
Mortal sin is a sin of grave matter
Mortal sin is committed with full knowledge of the sinner
Mortal sin is committed with deliberate consent of the sinner
This means that mortal sins cannot be done "accidentally." A person who commits a mortal sin is one who knows that their sin is wrong, but still deliberately commits the sin anyway. This means that mortal sins are "premeditated" by the sinner and thus are truly a rejection of God’s law and love.
One commits venial sin when, in a less serious matter, he does not observe the standard prescribed by the moral law, or when he disobeys the moral law in a grave matter, but without full knowledge or without complete consent.
Venial sin weakens charity; it manifests a disordered affection for created goods; it impedes the soul's progress in the exercise of the virtues and the practice of the moral good; it merits temporal punishment. Deliberate and unrepented venial sin disposes us little by little to commit mortal sin. However venial sin does not break the covenant with God. With God's grace it is humanly reparable. "Venial sin does not deprive the sinner of sanctifying grace, friendship with God, charity, and consequently eternal happiness."
Some men brought their friend to Jesus. The man was paralyzed and could not move. His friends believed that Jesus could make him well, but they couldn't even get in the door.
They had an idea. They would find another way into the house. If they could get up on the roof, they could remove a part of the roof and make a hole above the crowd. That is just what they did. Then they attached ropes to the bed on which their friend was lying and slowly lowered him down into the room, right in front of Jesus When Jesus saw their faith, he said, "Son, your sins are forgiven.
So to prove to them that he could forgive sins, He did the harder thing. He said, "Take up your bed and walk." And the man who had been unable to move, stood up and walked. Everyone could see what had happened as a result of Jesus' words. The people could hardly believe their eyes. They had never seen such power