In a matter so delicate as the one now under consideration, we cannot be too precise. It is certain that must die in the state of grace in order to be saved, and that this suffices. It would appear then that for the faithful in the world, there is no other obligation than that of preserving the state of grace. However, the question is precisely whether they can preserve the state of grace for a long time without striving to grow in holiness. To this, authority and reason enlightened by faith answer that, in the state of fallen nature, one cannot for long remain in the state of grace without striving at the same time to make progress in the spiritual life and to exercise oneself from time to time in the practice of some of the evangelical counsels. —The Spiritual Life, 354, Tanquery
Suppose that someone attending a dance or concert had to spend the time suspended by a rope, with his head hanging down. Could he enjoy the entertainment? Yet such is the state of a Christian who has made himself an enemy of God. It’s as if his soul is turned upside down: Instead of being united with God and detached from created things, he’s united with created things, and separated from God.
Sinners are like people parched with thirst and placed standing up in the middle of a fountain. Because the waters flowing around them don’t enter inside them to quench their thirst, in the midst of the water they remain thirstier than before. In addition, sin brings with it the remorse of conscience—a cruel worm that gnaws incessantly and never dies (see Isaiah 46:24). A sinner may go to a festival, to a comedy, to a banquet. But even there, his conscience continually accuses him, saying: “Unhappy man! You’ve lost God! If you were to die right now, what would become of you?”
The torment of remorse of conscience is so great, even in the present life, that some people have put an end to their lives just to escape it. If sinners would suffer for God what they suffer for sin, they would lay up great treasures for eternity, and would lead a life of peace and happiness. —St. Alphonsus Liguori, Sermon on the Unhappy Life of Sinners