[Esaias]

"(however, forgiveness CAN be "cancelled" according to Scripture, under certain conditions)"

I can already see people's eyes bulging out upon reading this, so let me provide some Scripture to ease everybody's worried minds:

The soul that sinneth, it shall die. The son shall not bear the iniquity of the father, neither shall the father bear the iniquity of the son: the righteousness of the righteous shall be upon him, and the wickedness of the wicked shall be upon him. 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. All his transgressions that he hath committed, they shall not be mentioned unto him: in his righteousness that he hath done he shall live. Have I any pleasure at all that the wicked should die? saith the Lord GOD: and not that he should return from his ways, and live? 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. Yet ye say, The way of the Lord is not equal. Hear now, O house of Israel; Is not my way equal? are not your ways unequal? When a righteous man turneth away from his righteousness, and committeth iniquity, and dieth in them; for his iniquity that he hath done shall he die. 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. Because he considereth, and turneth away from all his transgressions that he hath committed, he shall surely live, he shall not die. Yet saith the house of Israel, The way of the Lord is not equal. O house of Israel, are not my ways equal? are not your ways unequal? 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. 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? For I have no pleasure in the death of him that dieth, saith the Lord GOD: wherefore turn yourselves, and live ye.
(Eze 18:20-32)

Here, if a righteous person turns from righteousness to sin, their righteousness is not going to be remembered. So if a person repents, and then falls back into sin, their previous repentance and forgiveness will not be remembered. It will in effect be cancelled. We see Jesus illustrating and affirming this same exact principle:

Therefore is the kingdom of heaven likened unto a certain king, which would take account of his servants. And when he had begun to reckon, one was brought unto him, which owed him ten thousand talents. But forasmuch as he had not to pay, his lord commanded him to be sold, and his wife, and children, and all that he had, and payment to be made. The servant therefore fell down, and worshipped him, saying, Lord, have patience with me, and I will pay thee all. Then the lord of that servant was moved with compassion, and loosed him, and forgave him the debt. But the same servant went out, and found one of his fellowservants, which owed him an hundred pence: and he laid hands on him, and took him by the throat, saying, Pay me that thou owest. And his fellowservant fell down at his feet, and besought him, saying, Have patience with me, and I will pay thee all. And he would not: but went and cast him into prison, till he should pay the debt. So when his fellowservants saw what was done, they were very sorry, and came and told unto their lord all that was done. Then his lord, after that he had called him, said unto him, O thou wicked servant, I forgave thee all that debt, because thou desiredst me: Shouldest not thou also have had compassion on thy fellowservant, even as I had pity on thee? And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him. So likewise shall my heavenly Father do also unto you, if ye from your hearts forgive not every one his brother their trespasses.
(Mat 18:23-35)

Here the servant was forgiven, but refused to forgive others. So his previous forgiveness was literally cancelled and the debt came due. "And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him. So likewise shall my heavenly Father do also unto you..."