Some of the most influential personalities in human history are those of the Greek philosophers and scholars, such as Plato, Socrates, and Aristotle. The Ancient Greeks worshipped many gods, but now there is evidence that some of the most influential of the Greeks may have been Muslim or very close to it.
Plato, for example, is considered the founder of modern monotheism. Even though he lived in Greece, in western philosophy the origin of monotheism is traced back to Plato. Plato's philosophy later played a large role in the development of Christian as well of Islamic thought. After the fall of Greece, the neo-platonistic tradition was kept alive in the then flourishing Islamic world.
Socrates was Plato's teacher. Almost all of his writings were destroyed, but from the records we have left, we find that encouraged the youth of Athens to question their ideas of gods (for which he was sentenced to death) and overall seems to be very Islamic in tone.
Plato's principal student was Aristotle. Aristotle's principles dominated the world for a millennium after his death. One example is the creation of logic. Never before in the history of mankind was logic discussed or taken as a science. There is absolutely no evidence of this before the time of Aristotle. This is astonishing to many historians, because they claim that every event in human history is based on an event that occurred before it. For example, Einstein's theory of relativity was based on works of previous scientist of the 19th and previous centuries. But never has anything or any philosophy been created ex nihilo -- out of nothing. Only the messengers of God can introduce entirely new knowledge or science. Therefore, in a way the creation of logic can be considered a kind of divine act. And indeed, Aristotle was in fact regarded as an ancient prophet by certain Medieval Islamic scholars and certainly as an intellectual messenger by the rest. Much of Ibn Sina's philosophy is based on the work of Aristotle.
Aristotle, furthermore, was the teacher of Alexander the Great. It has been argued by many Islamic scholars that the mention of the "Two-horned one" or Zul-qarnain in the 18th Chapter of the Holy Quran is actually referring to Alexander the Great. In this chapter he is presented as a righteous servant of God.
The Quran says that God has sent messengers to all nations, and it would seem illogical if God did not send prophets to the thriving civilization of the ancient Greeks. Given this and the fact that Alexander's teacher was Aristotle, whose teacher was Plato, and whose teacher was Socrates, linking them all to certain common beliefs, which could, in light of the above evidence, surely be Islam!