1. Twice we are told in this passage vs 19 & vs 26 that Jesus came to the disciples who were meeting behind locked doors, and in verse 19 we are told why "for fear of the Jews". the Jews had crucified their Lord and they feared being next on the list.
2. Did then Jesus words "peace" = shalom not dissolve this fear? well there is no rebuke of the disciples the second time for being behind locked doors. so in the passage perhaps the locked doors function to point out two things. First that Jesus resurrection body is both physical, one could touch the wounds in his hands and side, and yet supernatural - it passes through physical objects. Secondly that the circumstances of the appearance of Jesus to the disciples ( missing Judas who hung himself and Thomas ) are the same when Jesus appeared to Thomas, thus "informing" Thomas that what they had told him during the week wasn't a con! They hadn't colluded and fabricated the whole thing.
3. Peace for the Jews this alludes to the well being of God’s Kingdom people in His end time Kingdom.
4. During the week the disciples continually told Thomas of what had happened. elegon – an imperfect tense of repeated action “they kept saying".
5. Jesus shows the marks in his hands and his side, not hands and feet. for his was an unusual case of crucifixion. the spear thrust into his side to make sure he was dead so the body could be taken down and buried before the Sabbath.
6. it has been reported historically that during the Roman occupation of Israel that over 1 million people were killed and possibly of those 200,000 were crucified. Now the point is that of the incredible large number crucified very few would have had a spear mark in their side.
7. one in a million or at least one in 200,000? the following statistics were found on Body count of the Roman Empire
Durant, Caesar and Christ
Revolt of 68-73 CE: 1,197,000 Jews killed acc. to Josephus ix 3. 600,000 killed acc. to Tacitus v 13.
Revolt of 115-116 CE: 220,000 people k. in Cyrene and 240,000 k. in Cyprus
Revolt of 132 CE: 580,000 k.
[TOTAL: Adding gives a total of 1,920,000 ± 300,000 k. in the Jewish Wars according to ancient sources]
Most historians assume that Palestine simply couldn't support a population large enough to produce death tolls as large as these. Among the population estimates are
Anthony Byatt, "Josephus and population numbers in first century Palestine." Palestine Exploration Quarterly, 105:51 (1973): 2,265,000 inhabitants
C. C. McCown, 'The Density of Population in Ancient Palestine', Journal of Biblical Literature, 66:425 (1947): less than 1,000,000 inhabitants
Harnack, Die Mission und Ausbreitung des Christentums (1924): 500,000 inhabitants
Seth Schwartz, Imperialism and Jewish Society, 200 B.C.E. to 640 C.E. (2001): 500,000 inhabitants
8.Is Doubt something a Christian should not have? Well Thomas only asks for what the other disciples already experienced. Thomas thus gets a bad rap for being singled out.
9. What is Thomas' character? was he a hard nosed skeptic? a pessimist? We need to look at context and John 11:16f and John 14.
It is more likely Thomas was totally devoted to Jesus. He would go and die with him! so he didn't want to led on by the other disciples? after the crucifixion he was a shattered man.
10. Jesus said “be not unbelieving but believing”. how do we take this? as a command to stop doubting - like almost repent? a rebuke as such or is it a command to move on from your doubt - the sufficient evidence is before you.
11. We are not saying someone can intellectually work their way into heaven / salvation rather the emphasis is God has made man in His image with ability to reason, and this is what the Holy Spirit convicts. Luke 16:19-31 tells us that even miraculous resurrection one could deny because of hardness of heart. what is required is the work of the Holy Spirit. Significantly in both Luke and here It tells us Scripture is sufficient!
12. and that's the important thing about verse 29-31. in context they appear right after the Thomas encounter. John teaches us that Scripture is sufficient to be blessed of God.
13. lastly it isn't merely knowing about Christ, even Satan and his demons know Christ is God. it's about right relationship. one that means life - Jesus came to give fullness of life. not mere existing. getting by.
As you can see, much of the above attempts to deal with the literary structure, and context of the passage.