In apologetics, it is questionable if historical religious institutions and practices are judged by modern ethical standards. This is sometimes labelled as presentism and typically avoided by historians.  Comparison between historical and contemporary morality is enabled by a religion's claim to absolute morality and moral realism. If we are willing to abandon these concepts, it is entirely valid to claim that the Medieval period "was a different time" and it is not appropriate to compare it to current standards of behaviour. However, religions generally do subscribe to the idea of moral realism. If that assumption is allowed, and we write in an ethical but not necessarily historical context, comparison of morality between different time periods and places is valid.
This defense is sometimes used in relation to historical religious figures, such as Muhammad, who performed many actions that would be unacceptable in contemporary culture. Criticism of Muhammad is sometimes dismissed as presentism.  However, if Muhammad claimed to have a timeless absolute moral code, it is appropriate to discuss his actions in a contemporary moral context.