Religiosity does not equate to political conservativism.
Also, religiosity for Black people means something completely different than it does for whites.
White people are turning religion into a nationalist ideology that's tied to white supremacy and views anything that is diverse as anti-white and anti-American. That's been documented.
Black people are religious, but it's not tied to their ideas about who is an American and who should vote and how. Political conservatives advocate for small government which translates into less enforcement of civil rights. They do not believe in broad civil rights unless it's covered by the Constitution. Political conservatives believe in a strict interpretation of the Constitution and they advocate states' rights, which always translates into majority rules. Whites are the racial majority so the political conservative agenda pushes states' rights to represent whites' preferences and needs.