The WSJ explores the influences and supposedly hidden messages of Michelangelo in an interview with Roy Doliner:

Q: So these images aren’t exclusively Jewish?

What Michelangelo was doing was trying to remind Rome five centuries ago that Jesus was a Jew, he came from Jews, and that Christianity is based on Judaism. Florence in his time was proud of that connection, whereas Rome was not only trying to separate the two religions but to negate in great part its roots in Judaism — and even forcibly separate Jews and Christians. There were many Papal bulls outlawing fraternization and friendship between Jews and Christians, whereas in Florence everybody was partying together.

Q: Was Michelangelo simply promoting the Florentine agenda in Rome?

Absolutely. In his poems he complains about the abuses of power and hypocrisy of the church. It’s not us imagining it; it’s in his own words and work. This was not somebody who was thrilled about working for the Vatican on a ceiling.

Although today the message might be subtle, perhaps in his lifetime it was as open as his poetry.

One only has to be
finding windows and doors
a member among those with a key
to unlock what we all stare towards