Answer:
Murillo's popularity among the people of Spain was mainly due to his painting was strongly modeled by the Catholic faith he professed. Also his orphanhood, the experience of losing several children, the lean season and the plague ravaging the city in the late 1650s, made him develop a great sensitivity towards the homeless and those who suffer most in society, becoming an expert in gender scenes with poor children.
His expertise as a painter led him to receive commissions from the highest echelons, religious works were undoubtedly his forte, as he was able to reflect expressions, feelings and emotions on faces and bodies like no one else.