4 But I have this against you, that you have abandoned the love you had at first.5 Remember therefore from where you have fallen; repent, and do the works you did at first. If not, I will come to you and remove your lampstand from its place, unless you repent.
Revelation 2:5 (ESV)
5 Now I want to remind you, although you once fully knew it, that Jesus, who saved a people out of the land of Egypt, afterward destroyed those who did not believe. 6 And the angels who did not stay within their own position of authority, but left their proper dwelling, he has kept in eternal chains under gloomy darkness until the judgment of the great day— 7 just as Sodom and Gomorrah and the surrounding cities, which likewise indulged in sexual immorality and pursued unnatural desire, serve as an example by undergoing a punishment of eternal fire.
Jude 1:5-7 (ESV)
8 Watch yourselves, so that you may not lose what we have worked for, but may win a full reward. 9 Everyone who goes on ahead and does not abide in the teaching of Christ, does not have God. Whoever abides in the teaching has both the Father and the Son.
2 John 1:8-9 (ESV)
16 If anyone sees his brother committing a sin not leading to death, he shall ask, and God will give him life—to those who commit sins that do not lead to death. There is sin that leads to death; I do not say that one should pray for that.
1 John 5:16 (ESV)
15 Everyone who hates his brother is a murderer, and you know that no murderer has eternal life abiding in him.
1 John 3:15 (ESV)
24 Let what you heard from the beginning abide in you. If what you heard from the beginning abides in you, then you too will abide in the Son and in the Father. 25 And this is the promise that he made to us—eternal life.
1 John 2:24-25 (ESV)
6 If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth. 7 But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin. 8 If we say we have no sin, we deceive ourselves, and the truth is not in us. 9If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. 10 If we say we have not sinned, we make him a liar, and his word is not in us.
1 John 1:6-10 (ESV)
11 Since all these things are thus to be dissolved, what sort of people ought you to be in lives of holiness and godliness, 12 waiting for and hastening the coming of the day of God, because of which the heavens will be set on fire and dissolved, and the heavenly bodies will melt as they burn! 13 But according to his promise we are waiting for new heavens and a new earth in which righteousness wells. 14 Therefore, beloved, since you are waiting for these, be diligent to be found by him without spot or blemish, and at peace. 15 And count the patience of our Lord as salvation, just as our beloved brother Paul also wrote to you according to the wisdom given him, 16 as he does in all his letters when he speaks in them of these matters. There are some things in them that are hard to understand, which the ignorant and unstable twist to their own destruction, as they do the other Scriptures. 17 You therefore, beloved, knowing this beforehand, take care that you are not carried away with the error of lawless people and lose your own stability.
2 Peter 3:11-17 (ESV)
4 For if God did not spare angels when they sinned, but cast them into hell and committed them to chains of gloomy darkness to be kept until the judgment; 5 if he did not spare the ancient world, but preserved Noah, a herald of righteousness, with seven others, when he brought a flood upon the world of the ungodly; 6 if by turning the cities of Sodom and Gomorrah to ashes he condemned them to extinction, making them an example of what is going to happen to the ungodly; 7 and if he rescued righteous Lot, greatly distressed by the sensual conduct of the wicked 8 (for as that righteous man lived among them day after day, he was tormenting his righteous soul over their lawless deeds that he saw and heard); 9 then the Lord knows how to rescue the godly from trials, and to keep the unrighteous under punishment until the day of judgment, 10 and especially those who indulge in the lust of defiling passion and despise authority. Bold and willful, they do not tremble as they blaspheme the glorious ones, 11 whereas angels, though greater in might and power, do not pronounce a blasphemous judgment against them before the Lord. 12 But these, like irrational animals, creatures of instinct, born to be caught and destroyed, blaspheming about matters of which they are ignorant, will also be destroyed in their destruction, 13 suffering wrong as the wage for their wrongdoing. They count it pleasure to revel in the daytime. They are blots and blemishes, reveling in their deceptions, while they feast with you. 14 They have eyes full of adultery, insatiable for sin. They entice unsteady souls. They have hearts trained in greed. Accursed children! 15 Forsaking the right way, they have gone astray. They have followed the way of Balaam, the son of Beor, who loved gain from wrongdoing, 16 but was rebuked for his own transgression; a speechless donkey spoke with human voice and restrained the prophet’s madness. 17 These are waterless springs and mists driven by a storm. For them the gloom of utter darkness has been reserved. 18 For, speaking loud boasts of folly, they entice by sensual passions of the flesh those who are barely escaping from those who live in error. 19 They promise them freedom, but they themselves are slaves of corruption. For whatever overcomes a person, to that he is enslaved. 20 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 overcome, the last state has become worse for them than the first. 21 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. 22 What the true proverb says has happened to them: “The dog returns to its own vomit, and the sow, after washing herself, returns to wallow in the mire.”
2 Peter 2:4-22 (ESV)
5 For this very reason, make every effort to supplement your faith with virtue, and virtue with knowledge, 6 and knowledge with self-control, and self-control with steadfastness, and steadfastness with godliness, 7 and godliness with brotherly affection, and brotherly affection with love. 8 For if these qualities are yours and are increasing, they keep you from being ineffective or unfruitful in the knowledge of our Lord Jesus Christ. 9 For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins. 10 Therefore, brothers, be all the more diligent to confirm your calling and election, for if you practice these qualities you will never fall. 11 For in this way there will be richly provided for you an entrance into the eternal kingdom of our Lord and Savior Jesus Christ.
2 Peter 1:5-11 (ESV)