We sometimes here people saying words like: "a thorn in my side." What they basically mean is that someone or something has been continually causing problems for them, and the sooner they are able to get rid of such problems, the better. For example, some couples may have had money problems as a thorn in their side since the day they got married; or health inspectors are a thorn in the side of most restaurants; or custom officers have been a thorn in the side of crminals involved in smuggling activities due to raids and confiscation of smuggled goods.
In today's reading, we come across another example of a "thorn in my side." In the reading, two prophets who have been a plague to the world, were finally killed by the beast that comes out of the Abyss. This caused the people of the world to be glad about it, since they thought that the "thorn in their sides" have been finally gotten rid of. But God had other plans, and "after three-and-a-half days, God breathed life into them and they stood up, and everybody who saw it happen was terrified; then they heard a loud voice from heaven say to them, ‘Come up here’, and while their enemies were watching, they went up to heaven in a cloud." The thorn in the sides of the people of the world could not be silenced or stopped, since God is with them.
What does this mean to us? As Christians, we are called to be "a thorn in the side" of others, especially when it comes to doing what is right and just. We may face troubles or presecution, or even put to death, but we should not be worried or concerned, and continue being "a thorn in the side," since what we are doing is not for our own gratification or glory, but for the glory of God.