Boris Johnson’s government’s proposal to deport asylum seekers of whatever origin who arrive on unauthorised routes, such as by crossing the Channel, to Rwanda in east Africa is beyond callous. It is understandable that the archbishop of Canterbury, Justin Welby, should want to add his voice to the protests. But invoking God’s judgment in the matter leaves him vulnerable to a second question. If the Almighty did offer him such an opinion, what did He suggest be done instead? The government’s argument for deportation is bizarre. It is that people smugglers along the French coast are endangering the lives of refugees – so it is “bold and innovative” to arrest and expel the latter. To Jacob Rees-Mogg this is “almost an Easter story of redemption”. Redemption for whom? What do these people think they are doing? It is like reacting to a spate of burglaries by locking the victims outside their homes. Since tens of thousands of refugees crossed in small boats last year, but only low numbers are likely to face removal in the short term – and with legal challenges expected – Johnson’s gesture is pure headline fodder. He has even demanded that the first flights go within weeks, to be close to his critical May local elections. Was vote-grabbing ever more blatant? We know that the only solution to the Europe-wide migration crisis must lie in a long-term and agreed-upon EU policy towards the movement of people, particularly from Africa, the Middle East and Asia. For Britain, in particular, it must lie with France. When it was a member of the EU, Britain could at least seek collaboration on a joint policy, most critically along its Channel coast. While the chief argument for Brexit was to stop immigration, the reality has turned out to be that Britain’s membership of the EU has no bearing on the movement of those forced to leave their homes as a result of war, crisis and state failure. France has no need or incentive to help us. Handling migration requires political realism and sensitivity. Britain’s policy is chaotic thanks to the Home Office’s deployment of “hostile environment” as a tool of control. Anyone with personal experience of this knows it to be cruel, expensive and of limited effectiveness. Its ingrained bureaucratic obstructionism has given the lie to Johnson’s boast of an open door to Ukrainian refugees. That department’s permanent secretary has reportedly questioned the Rwanda policy as an unproven expense, only to be overruled by his boss, Priti Patel. Britain’s civil service is in a poor state if, when ordered to implement an unethical policy, it can object only on grounds of “value for money”. In which case, where were their objections to costly PPE procurement or HS2? As for God, where is He in all this? Welby is professionally entitled to claim priestly infallibility, though his distinction between a policy’s details, which he leaves “to politics”, and its principles that must “stand the judgment of God” needs exegesis. I always thought “the devil is in the detail” was a cop out. The days when an archbishop could plausibly speak for the conscience of the nation are over. Surveys now put “irreligious” Britons at 52% of the population and Welby’s Anglicans at below 12%. This need not affect a priest preaching to his own flock. But when a state-established church summons God to condemn an evil policy it merely confuses the forces that need mustering against it. They are forces not of religion, but of reason and common humanity. They must now confront a desperate politician’s latest attempt to save his own skin. Simon Jenkins is a Guardian columnist