If you look at the original Greek word here you will see that it is "eirene" which according to The Strongest NIV Exhaustive Concordance can be used to express: peace, harmony, tranquility; safety, welfare, health, often with an emphasis on lack of strife or reconciliation in a relationship, as when one has “peace with God". Often used as a verbal and written greeting.
Yet a week later, when once again Christ appeared to them, we are told that they were behind locked doors just as they were in today's scripture. Again He uttered the same words, "Peace be with you!
Go back and read how the concordance uses this word "eirene". Could it be a greeting? Certainly, but I am confident He was bringing them calm despite their fear for their situation as His followers.
We know shortly as we progress in our Bibles that they became emboldened and calm despite their situation as they became filled with the Holy Spirit and shared the Good News building the early church.
Had they stayed in fear locked up only together behind locked doors this church, our church would have never happened.
I find it interesting that even though they saw Christ the first time it wasn't enough to totally allay these fears. As Christ says to Thomas in the non included words from 20:29, "Because you have seen me, you have believed; blessed are those who have not seen and yet have believed."
That statement alone is a blessing for those down through the centuries who have since come to believe. But it makes me wonder about Christians who are in perilous times themselves now or for the times yet to come.
Christians who were told about Christ's resurrection and about His death for their sins will they have peace when the moment of peril comes?
Many in our world today will face persecution as followers of Christ up to and including death. How do you just read the words from today's scripture and have the peace to stand? The answer is probably they won't if that is all they have.
Put yourself in these disciples place all those years ago. You have heard the murderous threats and you flock together for safety, at least as far as you feel it, by being together.
What must you do to not betray Christ? For us it is the full armament of God such as we read about in Ephesians 6 a short time back. We get it here each week as we prepare for Sunday School and that is a good start. There is a gospel we have received and we see that word "eirene" used again in Ephesians 6, it is the gospel of peace.