The answer to this lies in the different moral and ethical codes held by the Churches; some have a sola scriptura law, based on the scriptures alone. This would be the Lutheran position. Some have a moral code based on natural law. This is the Catholic position.
Within religious communions, while there is faith, there is also a broad church wherein people may believe one thing and practice another.
Most of the Churches fail to provide a personal moral foundation to their adherents, but rather, present them with a set of propositions to believe, and a moral code to practice. There is no personal relationship with divinity, no development of conscience, and hence, believers act without consistency across a broad range of ecclesial communions.
Abortion tends to be a very emotional issue as it concerns the definition of life, the termination of life, and justification for same. Some call it murder; some call it justified in some circumstances, and some say Get your rosaries off my ovaries, which means, inter-alia, the woman makes the decision, not the Church.
Perhaps the ideal answer to the abortion issue is that the woman discuss the matter with God. After all, religion means experience, not speeches, not orations, not debates, not protest marches, not law courts, not the Supreme Court.
All Women and All Men must first grasp the Truth. All religious factions and fights will vanish, as fast as man grasps the Reality. For, the name follower of theistic code of morals, can be allotted only to one who has experienced God and realised His Glory.
Religion is all about experiencing God. Not fights about abortion.