How and why did the religious attitudes of the middle ages change during the renaissance

A lot of things contributed to a change of mind during the Renaissance period and the years immediately following it.

1) The redescovery of the ancient greek and roman classics. This fact can be seen in the works of Michelangelo, one of the greatest artists of all times. The human body, hidden for so long during the Middle Ages becomes a source of interest to the artists (sculpture) of the time.

2) The invention of press, by Gutemberg. This allowed the spread of knowlegde all over the western world. Specially the new, and many times disturbing, ideas by some thinkers and the newborn class of scientists.

3) The Protestant Reform by Luther and Calvin. Those two guys succesfully challenged an well established status quo maintained for more than 1000 years by the Catholic Church.

All those things contribuited to the formation of a new kind of man, more curious, more adventurous and courageous enough to question established truths, leaving his confort zone and, as consequence, embracing new worlds.

:-)