What is the calling of the 144,000?

The calling of the 144,000 is to testify to the world that Jesus is the Messiah. The world will become intoxicated by an unprecedented success of peace and prosperity during the Great Tribulation. The one global religion will glorify man, which constitutes spiritual fornication. Scripture makes it apparent that these 144,000 will have abstained from such activity. How they achieve it is through the blood of the Lamb. It is also safe to say that they will not participate in the global political religious fornication as well. Notice they are "...the firstfruits unto God and to the land," which corresponds with Romans 11:16, "For if the firstfruit be holy, the lump is also holy: and if the root be holy, so are the branches."