Final answer:
Zwingli and Calvin led to a decrease in religious art in Protestant regions through iconoclasm, paving the way for more secular art forms.
Step-by-step explanation:
Huldrych Zwingli and John Calvin, prominent figures during the Protestant Reformation, had a significant impact on religious art. Both engaged in iconoclasm, the destruction of religious imagery, which they believed were forms of idolatry.
Zwingli in Zurich even went as far as removing organs from churches and banning religious images altogether. On the other hand, in the Protestant Reformation, art that was retained began to reflect Protestant theology which depicted biblical stories accurately and emphasized salvation through divine grace.
Therefore, under the influence of leaders like Zwingli and Calvin, religious art in Protestant regions saw a substantial decline, giving rise to more secular forms of artistic expression such as landscapes and portraiture.