Worst Form of Oppression 8:39
And combat them until there is no more test and trials. Until the revealed law of Islam, obedience, and submission is for Allah. But, if they grant an end then there should be no assault, except against the disregardful persecutors.
Aggression is forbidden in Islam. If the aggressor shows a willingness to desist and have peace, then there should be no hostility. There exist terrible dictators, tyrants and corrupt people that oppress their public. But, the worst form of oppression is false worship.
It oppresses the intellect, and directly conflicts with the common intelligence that G-d gave us. Ignorance and misconceptions associated with confusing the ideal of G-d is the worst form of oppression.