Fredricks:
I am ascertaining how Catholics view losing their salvation.
Any man that is damned to spend eternity in the lake of fire is damned because he committed mortal sin and persisted in unrepentance to the end of his life. **Catechism of the Catholic Church
1037** God predestines no one to go to hell; for this, a willful turning away from God (a mortal sin) is necessary, and persistence in it until the end.
There is sin which is mortal … there is sin which is not mortal.
1John 5:16 -17
But as for the cowardly, the faithless, the polluted, as for murderers, fornicators, sorcerers, idolaters, and all liars, their lot shall be in the lake that burns with fire and sulphur, which is the second death."
Rev 21:8
…nor did they repent of their murders or their sorceries or their immorality or their thefts.
Rev. 9:21
Do not be deceived; neither the immoral, nor idolaters, nor adulterers, nor sexual perverts, nor thieves, nor the greedy, nor drunkards, nor revilers, nor robbers will inherit the kingdom of God.
1Cor. 6:9-10
Now the works of the flesh are plain: fornication, impurity, licentiousness, idolatry, sorcery, enmity, strife, jealousy, anger, selfishness, dissension, party spirit, 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. 5:19-21
For it is impossible to restore again to repentance those who have once been enlightened, who have tasted the heavenly gift, and have become partakers of the Holy Spirit, and have tasted the goodness of the word of God and the powers of the age to come, if they then commit apostasy, since they crucify the Son of God on their own account and hold him up to contempt.
Heb 6:4-6
For if we sin deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, but a fearful prospect of judgment, and a fury of fire which will consume the adversaries.
Heb 10:26-27
For if, after they have escaped the defilements of the world through the knowledge of our Lord and Savior Jesus Christ, they are again entangled in them and overpowered, the last state has become worse for them than the first. For it would have been better for them never to have known the way of righteousness than after knowing it to turn back from the holy commandment delivered to them. It has happened to them according to the true proverb, The dog turns back to his own vomit, and the sow is washed only to wallow in the mire.
2Pet 2: 20-22