I've heard many people state that it was the punishment inflicted by the Romans that allows God to forgive us. This just doesn't make any sense to me. How can a man suffer for a short while here on earth in order that a divine being have the right to forgive sin?
Let's start with your question title. For the sake of argument let's turn it around and ask "Why would God not be allowed for forgive us?" The problem lies in God's idea of justice. We could spend a lot of time one this one, but let's keep it it simple:
In order for Him to actually be just, he has to administer justice. In order for justice to be adminstered the proper recompense has to be made for any wrong-doing. We know that the only way to pay for sin is death:
So we have to die. Or somebody has to die for us. The only person qualified to do that is Christ. The why is a subject for another question. Let's skip to what Christ did. When he was on the Cross he took upon himself the full wrath of God against all our sins.
God chose to crush Him. The pain inflicted by the Romans was nothing compared to the weight of that wrath. Even humans can endure the torture of crucifixion for the amount of time Christ did ... longer in fact. The difference was that while the physical act was in progress he also bore an infinite amount of punishment from His own Father. How does that work out for those who believe in Him?
To round this out I would point out that from a Reformed Protestant perspective, the notion that anything the hands of men could inflict upon Christ, no matter how brutal the Romans were could do anything to change God's ability to do or not do something is considered heretical. What Christ endured at the hands of the Romans an in crucifixion is both symbolic of a spiritual reality that was going on behinds the scenes, but also real in that that it put the rulers and authorities of this world to open shame while at the same time setting the stage for his physical resurrection to demonstrate his victory over death.
It's important to remember that there were two separate things happening here. The Crucifixion was only the end of the Atonement, which needed to cover both aspects of the Fall: sin and death.
When Christ was taken by the Roman soldiers, he wasn't still at the scene of the Last Supper, where Judas had been before he left to go betray him. He went up to the Mount of Olives, to the Garden of Gethsemane, and it was there that he took upon himself the sins of the world. He had done everything the Father asked of him thus far, but it was at this one point alone that we ever see any hint of hesitation, when he pleaded, "if it be possible, let this cup pass from me, nevertheless not as I will, but as thou wilt."
Here we have the Perfect Man, who has literally never sinned in his life, being asked to take upon himself the spiritual punishment for all the sins of the world. That's a pretty horrible thing, when you think about it, and it was difficult even for a God to bear. "And his sweat was as it were great drops of blood falling down to the ground." It's hard to imagine what that could possibly be like. Some extreme ordeals, such as childbirth with complications, have been known to cause a very small amount of blood to leak through the skin like sweat. To have it happen generally surely means that something unprecedented is taking place, and to have the subject survive the experience is a miracle in itself!
But he did survive it, paying the price for our sins that we would not have to if we would repent. After that he was taken, betrayed and tried in a sham trial, condemned and sent off to his death on the cross. This was necessary since, even though he had already paid for our sins, there was still death to deal with. So he allowed them to crucify him, giving up his life voluntarily and not having it taken from him (John 10: 18) as evidenced by his sudden death while crying with a loud voice--most victims of crucifixion died slowly of exhaustion, and this would have been impossible ordinarily.
He had to give up his life so that he could take it again, conquering death and unlocking the Resurrection for everyone. It's important to remember that "as in Adam all die, even so in Christ shall all be made alive." (1 Corinthians 15: 22) That part wasn't our fault, so it's paid for unconditionally, for everyone. But our sins are our own choices, so we have to choose to have faith in him, repent of our sins and live according to the law of the Gospel to have them washed away in his blood.
Let us look at Matt 27 verse 27 through 31.
Now, let us look at Isaiah 53 verse 5.
By this explaination, Jesus was pierced for our transgressions, and he was mocked for our iniquities. He was essentially the lamb who was punished instead of us being punished.
Recall that in the Old Testament, God gave instructions to Israel on how to atone for their sins through the sin offering. No longer do we have to sacrifice a goat or a bull, as the price has been paid through Jesus Christ, the Lamb of God.
What granted us God's forgiveness wasn't so much that Jesus endured through pain and suffering, but rather that He offered Himself up for sacrifice.
Jesus provided forgiveness of sins before his crucifixion:
It was not his suffering that cause the forgiveness, but the sacrifice. Had he been beheaded, all the scriptures regarding his sacrifice would be just as valid.
However the way that he died was to fulfill prophecy:
The method of the death itself is not significant (outside of it fulfilling prophecy and allowing him a chance to forgive the thief on the cross). It is the sacrifice he made that allows for the sins to be forgiven
ANF01 - Clement 1st. ltr. to Corinth) Though your sins reach from earth to heaven, I and though they be redder than scarlet, and blacker than sackcloth, yet if ye turn to Me with your whole heart, and say, Father! I will listen to you, as to a holy people.” 40 Comp. Isa. i. 18. BLXX Isaiah 1:18
come, let us reason together, saith the Lord: and though your sins be as purple, I will make them white as snow; and though they be as scarlet, I will make them white as wool.”
Before God was manifested on Earth through Jesus, the Hebrews received forgiveness of sin from God. After the crucifixion people still receive forgiveness of sin from God. The Redemption paid by Jesus through the incarnation, the passion, and the crucifixion, washed all mankind of original sin, which had stained man since Cain and Able were born. We are all now washed in the blood of Christ. But when we sin, we must still ask God for forgiveness, and must believe we have received it.
Jesus had His own explanation of the consequences of keeping the laws.
Jesus said:Mt. 5: 17* ¶ Think not that I am come to destroy the law (Torah), or the prophets: I am not come to destroy, but to fulfill. 18 For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. 19 Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven. 20 For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven.
And: He that hath my commandments, and keepeth them, he it is that loveth me: and he that loveth me shall be loved of my Father, and I will love him, and will manifest myself to him.
There are some 70 commandments given by Jesus in the NT.
(Matthew 28:19-20 KJV) Go ye therefore, and teach all nations (Matthew 22:37-38 KJV) Thou shalt love the Lord thy God (Matthew 22:39-40 KJV) Thou shalt love thy neighbour EXODUS 20:1-17 (KJV) THE TEN COMMANDMENTS (Matthew 7:12 KJV) whatsoever ye would that men should do to you (Matthew 6:12 KJV) we forgive our debtors. (Mark 11:25-26 KJV) forgive, if ye have ought against any (John 3:7 KJV) Ye must be born again. (John 15:4 KJV) Abide in me, (Matthew 5:16 KJV; see Let your light so shine before men also Matthew 5:15) (Matthew 5:23-25 KJV) first be reconciled to thy brother, (Matthew 5:29-30 KJV) cut it off, and cast it from thee (Matthew 5:34-37 KJV) Swear not at all; let your communication be,Yea; Nay, (Matthew 5:38-39 KJV) resist not evil: (Matthew 5:40-42 KJV) Give to him that asketh thee (Matthew 5:43-45 KJV) Love your enemies, ... be the children of your Father (Matthew 6:1 KJV) do not your alms before men (Matthew 6:5-7 KJV) pray to thy Father which is in secret; use not vain repetitions (Matthew 6:9-15 KJV) After this manner therefore pray ye: (Matthew 6:16) when ye fast, be not, as the hypocrites, of a sad countenance: (Matthew 6:19-21) Lay not up for yourselves treasures upon earth lay up for yourselves treasures in heaven (Matthew 6:25-26 KJV) Behold the fowls of the air ... reap not, gather not (Matthew 6:34 KJV) Take therefore no thought for the morrow (Matthew 6:33 KJV) seek ye first the kingdom of God, and his righteousness (Matthew 7:1-2 KJV) For with what judgment ye judge, ye shall be judged (Matthew 7:6 KJV) Give not that which is holy unto the dogs (Matthew 7:7 KJV) Ask, and it shall be given you; seek, and ye shall find (Matthew 25:34-36 KJV) -2 ye gave me meat; ye took me in: ye clothed me: ye visited me: ye came unto me. (Matthew 7:13-14 KJV) Enter ye in at the strait gate and few there be that find it (Matthew 7:15 KJV) Beware of false prophets (Matthew 10:1 KJV) to heal all manner of sickness and all manner of disease. Matthew 10:8 KJV) Heal the sick, cleanse the lepers, raise the dead, cast out devils: (Matthew 18:10 KJV) despise not one of these little ones (Matthew 23:8-12 KJV) - 5 be not ye called Rabbi: call no man your father upon the earth Neither be ye called masters: But he that is greatest among you shall be your servant. whosoever shall exalt himself shall be abased; he that shall humble himself shall be exalted (Matthew 18:15-17 KJV) - 3 go and tell him his fault between thee and him alone: take with thee one or two more, tell it unto the church: (Mark 11:22-24 KJV) - 2 Have faith in God. shall not doubt in his heart, but shall believe when ye pray, believe that ye receive them (John 15:12 KJV) love one another, as I have loved you. (Luke 22:19-20 KJV) do this in remembrance of me. (John 13:14 KJV) ye also ought to wash one another's feet. (Luke 6:35b KJV) Be ye therefore merciful (Matthew 28:19-20 KJV) Go ye therefore, and teach all nations, baptizing them (John 14:15 KJV) keep my commandments. (Luke 12:40 KJV) Be ye therefore ready also