Many of those who are against abortions have stances rooted in religious texts and beliefs. Thus in secular states, deciding whether or not one should be allowed to have an abortion should ideally be backed by scientific and empirical evidence surrounding the benefits and drawbacks of legal abortion rather than being drawn by religious fervor.
While it may not be explicit, abortion laws in many secular countries are largely underpinned by religious beliefs. For instance, in 2019 Alabama signed into law sweeping laws largely restricting abortion, even in cases of rape and incest. After it was signed into law, Governor Kay Ivey said that “this legislation stands as a powerful testament to Alabamians’ deeply held belief that every life is precious and that every life is a sacred gift from God." This is fundamentally a contravention of the secular values of the separation of Church and State. The State has no right to force religion on anyone, especially not through restrictive laws trying to control what women do with their bodies.
Although a state itself may not be technically religious, religious politicians are elected to uphold their constituents' beliefs. Religious constituents who elect a religious candidate expect them to reflect this - this is not immoral, it's the politicians job.
[P1] Secular states should not pass laws underpinned by religion. [P2] Restrictive abortion laws in secular countries are often accompanied by religious rhetoric.
Rejecting the premises
[Rejecting P1] Politicians in secular states do not have to completely reject religion if their citizens expect the politicians to reflect their beliefs.