Aside from his intelligence and wisdom, Socrates invented a new style in conversation, and priests were threatened by his inner voice. He was also accused of corrupting the social system and not valuing the Greek gods of the time.
Many people have learned about Socrates through the writings of his students, Xenophon and Plato, as well as the comic playright, Aristophanes. The latter wrote about the rise and fall of the Greek "Golden Era"; an era which Socrates witnessed.
The aspect that Socrates was best known for was his intelligence. His main profession was philosophy, and he expanded on this to develop systemic ethics and formal logic. Socrates became one of the founders of Western philosophy.
Socrates told people that he made most of his decisions through the guidance of an inner voice. This aspect got him into difficulties with the priests as they felt threatened by him.
He invented a new style of conversation which is now referred to as the "Socratic Method." This involved asking lots of questions until finally reaching an answer, rather than simply conveying information. This was based on his philosophy that "true wisdom is drawn from knowing that you know nothing" and is why he was accused of corrupting the entire social system.