To understand the Bible book of Revelation, as well as the rest of the Bible, a person has to be in touch with those whom God uses as his "prophets".(see Matt 24:45-47 whereby Jesus said that spiritual food would be dispensed by a "faithful and discreet slave" during our time period, during Jesus invisible "presence", Matt 24:3)
When Babylonian king Nebuchadnezzar had a dream of an "immense image", though he sought understanding from his magic-practicing priests and conjurers, they were unable to provide an explanation of its meaning.(Note: they were unable to tell king Nebuchadnezzar even what his dream was)
However, God had one of his people, a "prophet" named Daniel (Matt 24:15), to both reveal the dream and its meaning, for Daniel said: "None of the wise men, conjurers, magic-practicing priests, or astrologers are able to tell the king the secret that he is asking. But there is a God in the heavens who is a Revealer of secrets, and he has made known (through Daniel) to King Nebuchadnezzar what is to happen in the final part of the days (or "last days" [2 Tim 3:1], our time frame in history)".(Dan 2:27, 28)
Jesus even showed that the most literate or well educated people will be unable to accurately make sense of the Bible on their own, such as Revelation and its series of visions, as well as Daniel and its revealing of a succession of world powers (Dan 7) as well as the who the "king of the south" and the "king of the north" that are engaged in a conflict (Dan 11) to what is the meaning of Genesis 3:15 concerning the promised offspring to what God's Kingdom is.
Jesus said: "I publicly praise you, Father, Lord of heaven and earth, because you have hidden these things from the wise and intellectual ones (university graduates with PhDs etc, highly skilled ones, those with considerable abilities and knowledge, but who have an air of superiority) and have revealed them to young children (or humble, teachable ones who follow the leadings of God's holy spirit). Yes, O Father, because this is the way approved by you (to hide Scriptural understanding from those not qualified to grasp it)."(Matt 11:25, 26)
So, now let's get down to "brass tacks" and unveil who "the image" is at Revelation 13:15. However, before this can be done, a person has to grasp several other characters in the Bible book of Revelation. For example, what is the "wild beast" that arose from the "sea", as seen at Revelation 13:1 and that is the creation of the "dragon", that has its "image" produced by the ' two horned beast that looks like a lamb but speaks like a dragon ' ?(Rev 13:11)
First off, lets see what the "sea" is from which the "wild beast" arises. The Bible is its own interpreter, for Isaiah 57:20 says: "But the wicked are like the restless sea that cannot calm down, and its waters keep tossing up seaweed and mire". Isaiah 17 says: "Listen ! There is a commotion of many peoples, who are as boisterous as the seas ! There is an uproar of nations whose sound is like the roar of mighty waters !".(Isa 17:12)
Hence, the Bible reveals what the "sea" is, the restless masses of mankind who are never satisfied with the status quo, who are always on edge, as Jesus said, always in a state of agitation.(Luke 21:25, King James Bible reads "perplexity")
They want political change, and from these masses of people came forth the wide array of political governments, from democracy to monarchy to oligarchy to a republic. Thus, the "dragon" or Satan (Rev 12:9) is the mastermind behind all the political governments that came in to existence after the global deluge, over 4,000 years ago.
Thence, the "wild beast" (with its seven heads and ten horns) is the composite body of all political governments that have been assembled over their millennia of time. The Bible book of Daniel is the key (the Bible is its own interpreter) to understanding that the "wild beast" are political governments as seen at Daniel 7:1-8, that identifies four "beasts", starting with ancient Babylon and closing out with the Roman Empire, but from it came forth the final world power ("in the final part of the days"), a "small horn", that became the 7th and final world power of Bible history, Britain/America.
Consequently, what is it that mirrors the feelings and thoughts of the political arena as a composite unit, being its own "image" whereby political governments can exercise their right to file grievances against other nations or pursue their own policies, though supposedly for peace ? Initially, it was the League of Nations that came into existence in 1920 at the behest of Britain and America (of which they never joined though the founders of it), but collapsed in 1939 with the outbreak of World War II.
This "image" of the "wild beast" is also known by another name, the "scarlet-colored wild beast" at Revelation 17:3. The color scarlet (as well as purple) is noted in the Bible as one of royalty.(Lam 4:5; Matt 27:28) The "scarlet-colored wild beast" is also seen as carrying a "woman" on its back, a "prostitute".
Revelation 17 says that "the (scarlet-colored) wild beast that you (the apostle John) saw was, but is not, and yet is about to ascend out of the abyss (death-like state), and it is to go off into destruction" means that after the collapse of the League of Nations in 1939 ("but is not"), that it would come back to life under a new name, ' ascending out of the abyss ' of inactivity and became the United Nations in October, 1945.
The "woman" riding on the back of the "scarlet-colored wild beast" is called Babylon the Great (Rev 17:5), that "has a kingdom over the kings of the earth" or political governments.(Rev 17:18) The name Babylon the Great is drawn from its prototype, ancient Babylon. Ancient Babylon was noted, not for its political capabilities, but rather for its extreme religiousness, albeit false, that spread throughout the earth.(Isa 47:1, 11-13; Jer 51:47)
Hence, this "woman" that prostitutes herself before the "kings of the earth" is none other than the world empire of false religion, that includes Christendom.(Rev 17:1, 2) It has rode on the back of the "image" or "scarlet-colored wild beast" for millennia, but very soon this "wild beast" will go from just basically being all bark to ripping apart this "woman" prostitute, at the instance of our Maker, Jehovah God, who puts it within the hearts of the political governments ("ten horns" under the direction of the "image of the wild beast" or "scarlet-colored wild beast", the United Nations) to destroy her.(Rev 17:16, 17)