They are related, but certainly the latter can be talked of coherently separately - if one chooses.
Equality can be argued for in terms of economics, game theory, the objective recognition of commonality between humans, and from many other avenues, without reference to religion.
Literally none of that makes any sense. Within the system of human dynamics, nothing within that system can place an a priori restraint on the "right" rules for the system's existence, and it is literally impossible to talk about anything objective from within an intersubjective system. You're running up against Godel.
It’s literally impossible for us to be where are without history as it was. It’s not an obligation for us to keep making kids aware Thomas Jefferson existed.