I'm more focused on the first part, I don't think many here would agree with that comment. But to the second part...
1 Corinthians 9:24-27 Do you not know that in a race all the runners compete, but only one receives the prize? So run that you may obtain it. [25] Every athlete exercises self-control in all things. They do it to receive a perishable wreath, but we an imperishable. [26] Well, I do not run aimlessly, I do not box as one beating the air; [27] but I pommel my body and subdue it, lest after preaching to others I myself should be disqualified
"Lest I myself become a castaway."
Galatians 5:19-21 Now the works of the flesh are plain: fornication, impurity, licentiousness, [20] idolatry, sorcery, enmity, strife, jealousy, anger, selfishness, dissension, party spirit, [21] 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.
"Why warn them about the possibility of not “inherit[ing] the kingdom of God” if they are in no danger whatsoever of losing it? That makes no sense. Why would Paul use the word “warn” if it didn’t also apply to real potential danger in the spiritual lives of his Galatian recipients?"
Galatians 5:1, 4 For freedom Christ has set us free; stand fast therefore, and do not submit again to a yoke of slavery. . . . [4] You are severed from Christ, you who would be justified by the law; you have fallen away from grace.
Ephesians 5:3, 5 But fornication and all impurity or covetousness must not even be named among you, as is fitting among saints. . . . [5] Be sure of this, that no fornicator or impure man, or one who is covetous (that is, an idolater), has any inheritance in the kingdom of Christ and of God.