KJV John 14
15 ¶If ye love me, keep my commandments.
21 He that hath my commandments, and keepeth them, he it is that loveth me[.]
23 If a man love me, he will keep my words[.]
24 He that loveth me not keepeth not my sayings[.]
KJV Luke 7:47 [T]o whom little is forgiven, the same loveth little.
These words, taken together, imply that whosoever does not keep the words, sayings, and commandments of Christ, the same is not forgiven - or, in other words, we are forgiven to the degree that we keep Christ's commandments.
KJV Luke 6:37 [F]orgive, and ye shall be forgiven[.]
This suggests that Christ's commandments, which are summed up by the Golden Rule, might alternatively be summed up as "FORGIVE;" that is, always and instantly forgive everyone of every debt and trespass: hold nothing against anyone, ever.
If, then, entrance into the kingdom of God is given only to the forgiven, then the only real sin - indeed, the unpardonable sin - is failure to forgive everyone of everything, including God himself, for their apparent or alleged trespasses or failures towards us.
KJV Matthew 18
21 ¶Then came Peter to him, and said, Lord, how oft shall my brother sin against me, and I forgive him? till seven times?
22 Jesus saith unto him, I say not unto thee, Until seven times: but, Until seventy times seven.
23 ¶Therefore is the kingdom of heaven likened unto a certain king, which would take account of his servants.
24 And when he had begun to reckon, one was brought unto him, which owed him ten thousand talents.
25 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.
26 The servant therefore fell down, and worshipped him, saying, Lord, have patience with me, and I will pay thee all.
27 Then the lord of that servant was moved with compassion, and loosed him, and forgave him the debt.
28 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.
29 And his fellowservant fell down at his feet, and besought him, saying, Have patience with me, and I will pay thee all.
30 And he would not: but went and cast him into prison, till he should pay the debt.
31 So when his fellowservants saw what was done, they were very sorry, and came and told unto their lord all that was done.
32 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:
33 Shouldest not thou also have had compassion on thy fellowservant, even as I had pity on thee?
34 And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him.
35 So likewise shall my heavenly Father do also unto you, if ye from your hearts forgive not every one his brother their trespasses.
This applies to all Christians who acknowledge the KJV Bible as authoritative.
As an aside, one does not normally get rich - come into possession of more than one actually needs - by always forgiving everyone every debt and trespass; rather, one normally gets rich by doing the opposite. Hence, this.
KJV Luke 6:24 But woe unto you that are rich! for ye have received your consolation.
The other woes Jesus pronounced can be likewise analyzed from the vantage of failure to forgive.