Those expecting a reflection to aid their fasting and penance on Ash Wednesday by tuning in to BBC Radio 4’s “Prayer for the Day” might have been surprised to hear a Scottish Presbyterian minister suggest that receiving ashes was akin to wallowing in sinfulness.In his two-minute slot, the Revd Johnston McKay, formerly BBC Scotland’s editor of religious broadcasting, recalled the first time he encountered someone wearing ashes at university in Glasgow and telling them: “You’ve got a dirty mark on your forehead.” Observing that Pope Francis led a traditional penitential procession in Rome, where ashes were sprinkled on his head, he said: “How much easier it is, often, to wallow in a self-obsessed preoccupation with our own wrongs rather than d