According to the Scriptures, what is the full punishment that is due sinners who disobey the Lord and refuse to repent of their willful and evil deeds?
A fair question.
@DaveXR650 has answered very well. Perhaps I can add just a few things more.
I think the key text is Romans 3:25-26.
'Whom God set forth as a propitiation.....' A propitiation is a an offering that takes away wrath. Puritan and other writers speak of a 'satisfaction' to God's justice.
'That He might be just and the justifier of the one who believes in Jesus.' Weknow that God is satisfied by the propitiation of Christ, because it was He who set Him forth. It is not for us to take issue with God and to say that Christ should have suffered more. Who are we to take issue with God?
'There is no greater fallacy than the argument which goes from man to God. It is a very common error today. People argue like that -- if this is true of us, they say, how much more so of God? As if God were in series with us!' (D.M. Loyd-Jones). If God is satisfied, who are we to argue with Him.
But there are three parts to the punishment of sinners in hell: pain, darkness and separation from God. The darkness is quickly dealt with.
'Now when the sixth hour had come, there was darkness over the whole land until the ninth hour' (Mark 15:33). By that time the Pharisees and others had probably got fed up with mocking and gone home; John had taken Mary back to his house; the other prisoners has fallen silent, and our Lord hung there in the darkness alone. But with reference to the pain, look also at Mark 15:23.
Then they gave Him wine mingled with myrrh to drink but He did not take it.' Why did He not take the wine mixed with myrrh? Because it was an analgesic. It would have given Him some slight relief from the appalling pain of crucifixion, and this He could not receive..
Finally, the separation from the Father. This, I believe, was the prospect that particularly horrified Him at Gethsemane.
"My soul is exceedingly sorrowful, even to death" (Mark 14:34). And Luke tells us that he sweated blood as He prayed. Many Christian martyrs have gone to their deaths with greater composure than our Lord seems to have done, but they of course, were expecting God to be with them in their sufferings. The Lord Jesus was faced with enduring them alone.
But at the ninth hour, the sun came out again, and
'Jesus, knowing all things were accomplihed, that the Scripture might be fulfilled, said, "I thirst!"' Propitiation had been accomplished; God's righeous anger against sin and sinners had been satisfied. Just two things remained to be done. One of those was our Lord's actual death, which followed almost immediately; the other was the fulfillment of Psalm 69:21.
'And for My thirst they gave Me vinegar to drink.'
I hope you will find that helpful.