Peace, compassion and forgiveness of wrongs done by others are key elements of Christian teaching. However, Christians have struggled since the days of the Church fathers with the question of when the use of force is justified. Such debates have led to concepts such as just war theory. Throughout history, biblical passages have been used to justify the use of force against heretics, sinners and external enemies. Heitman and Hagan identify the Inquisitions, Crusades, wars of religion and antisemitism as being "among the most notorious examples of Christian violence". To this list, J. Denny Weaver adds, "warrior popes, support for capital punishment, corporal punishment under the guise of 'spare the rod and spoil the child', justifications of slavery, world-wide colonialism in the name of conversion to Christianity, the systemic violence of women subjected to men". Weaver employs a broader definition of violence that extends the meaning of the word to cover "harm or damage", not just physical violence per se. Thus, under his definition, Christian violence includes "forms of systemic violence such as poverty, racism, and sexism".