Is it permissible to donate to a Christian to help him pay off his debts so that he does not go to prison?

Allah has commanded kindness to all people and has not forbidden showing kindness and justice to non-Muslims. Rather, He has even allotted a share of zakat to those whose hearts are to be reconciled. It is preferable to direct spending towards the welfare of Muslims, especially since many of them cannot find their sustenance. However, it is permissible to give money to this Christian if doing so will reconcile his heart to Islam and show him the good character of Muslims.