Salvation is the only subject where there can be no compromise of doctrine.  

Conversion is linked with repentance.  True repentance is a covenant with God to cease from all known sin completely and forever, with the mind that even if it were to cost you your life to obey, you would do it.

One must also have the understanding that if we turn back to willful  sin - like the dog to his vomit -  we will be lost forever.

Following are the verses in Ezekiel which prove that repentance is a one time event,  and that one must cease from willful sin completely and forever  in order to "live".  

EZE 18:9 [He that] HATH WALKED in my statutes, and HATH KEPT my judgments, to deal truly; he is just, he shall surely live, saith the Lord GOD.

EZE 18:21  But if the wicked will turn from ALL his sins that he hath committed, and keep all my statutes, and do that which is lawful and right,  he shall surely live, he shall not die.

EZE 18:24  But WHEN the righteous turneth away from his righteousness, and COMMITTETH INIQUITY, and doeth according to all the abominations that the wicked man doeth, shall he live? All his righteousness that he hath done shall not be mentioned: in his trespass that he hath trespassed, and in his sin that he hath sinned, in them SHALL HE DIE.
EZE 18:27  Again, WHEN the wicked man turneth away from his wickedness that he hath committed, and DOETH that which is lawful and right, he shall save his soul alive.

28  Because he considereth, and TURNETH AWAY FROM ALL his transgressions that he hath committed, he shall surely live, he shall not die.

EZE 18:30  Therefore I will judge you, O house of Israel, every one according to his ways, saith the Lord GOD. Repent, and turn yourselves from ALL YOUR TRANSGRESSIONS; so iniquity shall not be your ruin.

31  Cast away from you ALL your transgressions, whereby ye have transgressed; and make you a new heart and a new spirit: for why will ye die, O house of Israel?

EZE 33:12  Therefore, thou son of man, say unto the children of thy people, The righteousness of the righteous shall not deliver him in the day of his transgression: as for the wickedness of the wicked, he shall not fall  thereby IN THE DAY THAT HE TURNETH
from his wickedness; neither shall the righteous be able to live for his righteousness IN THE DAY THAT HE SINNETH.

EZE 33:14  Again, when I say unto the wicked, Thou shalt surely die; if he TURN FROM HIS SIN, and do that which is lawful and right;

15  If the wicked restore the pledge, give again that he had robbed, walk in the statutes of life, WITHOUT COMMITTING INIQUITY; he shall surely live, he shall not die.

EZE 3:21  Nevertheless if thou warn the righteous man, that the righteous SIN NOT, and HE DOTH NOT SIN, he shall surely live, because he is warned; also thou hast delivered thy soul.

The last two verses make clear what Yahweh meant in the previous verses.  "Sin not...doth not sin...without committing iniquity"  These are all absolutes; sin not means "not ever".    Repentance is truly done only once, (notice the "in the day that he turneth" in 33:12 above.)

If a man commits sin, he has not truly repented in the first place, or if he has repented and turns back by committing deliberate sin "in the day that he sinneth"  he shall not live.

Paul taught the same thing in Hebrew 10:26 when he said:

"For if we SIN WILFULLY after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,

27  But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.

28  He that despised Moses' law died without mercy under two or three  witnesses:

29  Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?

You can see that same idea of only one true repentance in Hebrews 6:4
"For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,

And have tasted the good word of God, and the powers of the world to come,

If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.

Harold Kupp