Breakfast with Solomon - Matthew 24:14
"But this gospel of the kingdom shall be preached in the whole world as a testimony to all the nations, and then the end will come"
According to Jesus this is the reliable sign that signals the end of the age and the coming of Jesus Christ: when all the world has heard the good news of the kingdom. God will not bring the end of the world until every nation, tongue, tribe, and people have heard the gospel.
This is the working of the God who so loved the world that He gave his only begotten Son that whosoever believeth in Him shall not perish but shall have eternal life.
All of the other signs that have been mentioned in the 11 verses that precede this are really false signs that will constantly appear during the period preceding the end. These signs were present in increasing numbers before the destruction of Jerusalem. They have been a part of every 100-year period from Christ to the present. They feel like they could portend the end, but it is this sign of the gospel's penetration that is really the end.