The beginning of the Renaissance in the mid-fourteenth century was marked by a turn from medieval life and values dominated by the Church toward the philosophical principles of humanism. The major influences of the Italian Renaissance that changed art and religion were the questons being asked by scientist/artists like Leonardo DaVinci; writer, Francesco Petrarch, often known as the founder of humanism and scientists such as Copernicus and Newton who discovered mathematical relationships between objects and questioned known "religious" explanations for objects in space etc.
The Italian Renaissance was a period of looking back into the classical age of the Greco-Roman period of art, form and philosophy. Writers valued classical philosophy of Plato, Aristotle and Socrates over the more current schools of thought.
Discoveries in anatomy, math and science caused Renaissance thinkers to question the authority of the church and to develop a new humanistic school of thought that valued the human creature as God's greatest creation. This highly glorified view of humanity is seen in Renaissance art depictions of the Madonna, David, and La Pieta. The authority and "correctness" of a geo-centric universe is questioned by Copernicus who was told by church authorities that his "science" was heritical.
Art works were primarily sponsored by rich and the Church. The expressions on the faces of the Renaissance sculptures and paintings are much more alive than those of previous periods partly due to discoveries of anatomy and science. The realism in the art is a nod to the classical Greek and Roman artworks that had been recently re-discovered.