Religion has never been a private matter - practice of religion gives identity, the nature of that practice makes one visible or invisible in a larger whole. Religion therefore has to be a major tool in the hands of those who seek political power or clout. The element of power has created such close relationship between religion and violence. All major religions, Catholicism, Protestantism, Judaism, Islam, Hinduism, Sikhism and Buddhism are tainted with violence.
Violence is said to be not part of any religion but when religion is the matrix within which identity is crafted, violence gets embedded in religion.
The sheer number of people - just in the sense of population - frightens humanity because humans have demonstrated consistent capacity to harm and destroy. The fear, therefore, is not unfounded. The fear then becomes the basis for social organizing, whether it is through the family or religion or any other institution which can assure the larger society that things will not go haywire and that they are not at each-other's mercy. Family, clan, religion, etc are some of the oldest institutions that have been set up to organize the society in a manner that the social as well as personal behaviours stay within certain agreeable boundaries. Since these are human creations, they can be used by humans to serve or dis-serve the humanity.
Since religion carries with what people regard as incomprehensible truths - truths which cannot be easily understood by ordinary beings and the only way to benefit from those truths is by placing their blind trust in them - even the state has often bowed before the power of religion. State and politics aim to command allegiance and compliance for the right or wrong reasons and religion has historically demonstrated its ability to galvanize allegiance and compliance. It is not surprising, therefore, that the state and politics use and abuse religion.
So while it can be said that religion does not carry violence, if eyes and ears are kept open, it can be seen that by its nature religion makes violence pursue it. And to say that religion and violence are completely divorced is not to recognise that many form of practices of religion condone violence when it takes place in form of animal sacrifice or identity politics killigs. Religion is what people practice, ie, the reality of religion lies in its practice, not in the texts that the majority have not read, cannot read or cannot understand. And religions, even in their purest forms, have tended to stand side by side with violence.
Since religion is so close to the core of human beings, the political and state machinery mix up with religions allow them to acquire much greater role. Since it is believed to have come from a supreme power, who all can trust and who can solve all problems of humanity and so on, it also gains the legitimacy to be the factor that should direct every day actions of human beings. Where that happens, it is not impossible to see how religion begins to influence practice of social justice, gender equality, rights, etc. And in societies where more than one religion exists, the competition among them is directly correlated with the level of religious involvement in violence and political involvement in religions.