When will the Second Coming occur? In Matthew, Jesus seems to allude that the Second Coming will occur within his generation.
Truly, I say to you, this generation will not pass away till all these things take place.
Matthew 24:34 (RSV-2CE)
And in Mark, it is made more explicit.
And he said to them, “Truly, I say to you, there are some standing here who will not taste death before they see the kingdom of God come with power.”
Mark 9:1 (RSV-2CE)
However, in the later part of Matthew, Jesus said that the time of the Second Coming is unknown.
But of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father only.
Matthew 24:36 (RSV-2CE)
There is also the same contradiction in the letters of St.Paul. In 1 John, St.Paul said:
Children, it is the last hour, and as you have heard that antichrist is coming, so now many antichrists have come; therefore we know that it is the last hour.
1 John 2:18 (RSV-2CE)
But in 1 Thessalonians:
For you yourselves know well that the day of the Lord will come like a thief in the night.
1 Thessalonians 5:2 (RSV-2CE)
So, did Jesus and St.Paul expect the Second Coming to occur within their generation or not?