What does Secular mean? How does it relate to the Renaissance?

Not religious, strictly apart from any spiritual connotation. The renaissance was Europe moving away from the catholic church and religion in general. Towards move of a secular lifestyle and belief.

Secularism comes from the word secular, meaning "of this world". Before the Renaissance, medieval Christian civilization had been largely concerned with faith and salvation in the afterlife ... The art of the period in particular exhibited this secular spirit, showing detailed and accurate scenery, anatomy, and nature.

I hope this answers your question.

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