The use of religious themes in renaissance art was the most recognizable part of the renaissance and the average persons understanding of it today. This is however contrasted by the heavy humanistic themes in paintings from the Renaissance. Although some use of it was tied into the Church, a major part of the renaissance and why it allotted for many of mankinds' innovations was due to the fact that it strayed from studies of religion and focused on other studies, one of the most major ones being what it means to be human and humanity ( humanism ).
This was depicted in much of the art at the time.
'Primavera' by Sandro Botticelli, 1482
Paintings like these tended to stray away from the Church and religious themes. Other works of art, such as the Vitruvian Man by Leonardo da Vinci ( depicted below ), also touched upon the study of the human body. The Vitruvian Man is simply a proportional drawing of a man, and the surrounding text describes the proportions of the human body and can also be used as a guide to drawing a person in that sense.
In addition to the surplus of individualistic illustrations, humanistic themes also seeped into paintings in the Church. Many murals on Church walls like that of Michelangelo's murals upon the walls of the Sistine Chapel depicted biblical tales. The paintings usually portray human figures from the stories in the Bible, like that of the Virgin Mary and Moses.
In addition to already human figures from the Bible painted on the walls, an interesting detail is that there are humanized figures from biblical stories such as angels ( painted as cherubs ). The cherubs are angels, not historically accurate to the description of them in the Bible. They were cute and dainty, with a femme look to them. ( depicted below ).
'Vitruvian Man', Da Vinci circa 1490.
The change was very drastic, as the cherub is also symbolic of angelic innocence, much like that of a baby which is why they are depicted as such. Angels ( besides that of a cherub ) are also painted different during this time. The depiction of them changed because they were perceived differently by people at this time, thus making them painted more human.
( Left depicting biblically accurate angel, on the right is an image of two cherubs ).