What is a secular government?

Defined briefly, secularism means that governments should remain
neutral on the matter of religion and should not enforce or prohibit
the free exercise of religion, leaving religious choice to the liberty of
the people.

The concept of a secular government arose during the Enlightenment.  Freedom of personal belief and conscience enables citizens to use reason to determine the truth of a claim. The place of government is to ensure that this right is protected.

One form of secularism is asserting the right to be free from religious
rule and teachings, or, in a state declared to be neutral on matters of
belief, from the imposition by government of religion or religious
practices upon its people.

Another form of secularism is the view that public activities and
decisions, especially political ones, should be uninfluenced by
religious beliefs or practices. (https://en.wikipedia.org/wiki/Secularism)

A secular state is a country where the state is kept separate from
religion and the state does not discriminate against or favor persons based on their religious beliefs.