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.
The greatest influence of the Italian Renaissance was the work of Humanist scholars and renewed interest in classical learning. Medieval religion was based on the idea that human beings are basically flawed creatures with little worth. This idea is reflected in the art of the time which is primarily symbolic rather than realistic. With Humanism came the idea that human beings were God's greatest creation and therefore did have some basic worth. This is also reflected in Renaissance Art, as human beings are shown quite realistically, as in Michaelangelo's work on the Sistine Chapel ceiling. Realism is enhanced by adding perspective to give paintings dimension. The influence of classical learning is reflected in paintings and sculptures of Biblical figures who bear striking resemblances to Greek Gods. Examples are Michelangelo's statue of David, and the Creation of Adam (again on the Sistine Chapel ceiling) in which God bears a striking resemblance to Zeus. Interest in classical learning also caused scholars to question translations of the Bible. The extant translation was the Vulgate, by St. Jerome. Erasmus among other scholars re-translated the Bible from the original Greek and Hebrew, and found numerous errors. So, the influences on art and religion were to say the least quite monumental.