Relics

 The physical remains of the holy dead were hugely important from the earliest years of Christianity. Whereas Roman culture had seen human corpses as menacing and polluting, Christians saw them - or the holiest of them at least - as one of the most direct ways of accessing the power and virtues of the heavenly realm. For many millions of modern Catholic and Orthodox Christians, of course, this continues to be the case.
In the first millennium, saints' bodies were usually kept intact, not divided up and disseminated as they were in later centuries. St Oswald was mutilated and dissected on the battlefield, not by the followers of his cult. St Oswald's head ended up in the custody of the church of Lindisfarne, where it was kept with the relics of St Cuthbert. It may well still lie with St Cuthbert's bones, now in Durham Cathedral.
 

 A Victorian stained-glass window of St Cuthbert holding St Oswald's head, from Bolton Abbey in Yorkshire.