We can do this; but fact will still remain that if a believing Christian somehow is convinced to no longer believe; then he is NOT going to Heaven.
1. But there were also false prophets among the people, just as there will be false teachers among you. They will secretly introduce destructive heresies, even denying the sovereign Lord who bought them--bringing swift destruction on themselves.
2. Many will follow their shameful ways and will bring the way of truth into disrepute.
3. In their greed these teachers will exploit you with stories they have made up. Their condemnation has long been hanging over them, and their destruction has not been sleeping.
4. For if God did not spare angels when they sinned, but sent them to hell, putting them into gloomy dungeons to be held for judgment;
5. if he did not spare the ancient world when he brought the flood on its ungodly people, but protected Noah, a preacher of righteousness, and seven others;
6. if he condemned the cities of Sodom and Gomorrah by burning them to ashes, and made them an example of what is going to happen to the ungodly;
7. and if he rescued Lot, a righteous man, who was distressed by the filthy lives of lawless men
8. (for that righteous man, living among them day after day, was tormented in his righteous soul by the lawless deeds he saw and heard)--
9. if this is so, then the Lord knows how to rescue godly men from trials and to hold the unrighteous for the day of judgment, while continuing their punishment.
10. This is especially true of those who follow the corrupt desire of the sinful nature and despise authority. Bold and arrogant, these men are not afraid to slander celestial beings;
11. yet even angels, although they are stronger and more powerful, do not bring slanderous accusations against such beings in the presence of the Lord.
12. But these men blaspheme in matters they do not understand. They are like brute beasts, creatures of instinct, born only to be caught and destroyed, and like beasts they too will perish.
13. They will be paid back with harm for the harm they have done. Their idea of pleasure is to carouse in broad daylight. They are blots and blemishes, reveling in their pleasures while they feast with you.
You misapply 2 Peter 2 who as an apostle to the Jews (Gal 2:8) is mainly addressing the Jews and warning them about not relying on their own righteousness and self effort, the common theme regarding the Jews. The NT NEVER address Christians as "the ungodly". In the meantime, you are trying to turn "believing" into a work, thus espousing the false doctrine for justification by works.
The gospel of the grace of Christ IS the gospel. There is no other. There is no justification by grace AND works of the law. And to the degree you rely on works (including "believing" as a work) for your justification, to that degree you have FALLEN from grace.
"If by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then it is no more grace: otherwise work is no more work." Rom 11:6.
"Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace." Gal 5:4.
Your doctrine of works to stay saved is "another gospel" which is twice cursed.
"I marvel that you have turned away so soon from Him who called you in the grace of Christ, to a different gospel, which is not another; but there are some who trouble you and want to pervert the gospel of Christ. But even if we, or an angel from heaven, preach any other gospel to you than what we have preached to you, let him be accursed. As we have said before, so now I say again, if anyone preaches any other gospel to you than what you have received, let him be accursed." Gal 1:6-9.
Your doctrine of maintaining your salvation by the "work" of belief makes you subject to Satan's accusations and condemnation when you commit sins of unbelief, and espousing such to others makes you a candidate for the warnings in Galatians.
I think we're done here. Take care and good luck.