Here is senior research professor Tom Devine's reaction to the resignation of Cardinal Keith O'Brien.

My first reaction to Cardinal O’Brien’s resignation is one of personal sadness about the turn of events and also of human concern for the cardinal; his terrible suffering at this time can only be imagined.

Keith O’Brien has been a courageous leader of his  flock, well respected and  liked by many beyond the Catholic community and a doughty champion of his church who has spent a lifetime as pastor and teacher proclaiming its principles without fear or favour. Let him who is without sin cast the first stone.

The imprecise, anonymous allegations against the cardinal are not accepted, legal advice has been sought and nothing has yet been proven.

Nonetheless, and surprisingly perhaps, there is no denial of the charges in the formal announcement of resignation today; that must be a cause of concern.

This is probably the gravest single public crisis to hit the Catholic Church in Scotland since the Reformation and its effects in the short term are incalculable. Many of the faithful in Scotland will be stunned by the seismic turn of events and left demoralised.

But some perspective is necessary. The Church is very much more than episcopal hierarchies, no matter how eminent.

The powerful resilience of a global faith – accounting for one-sixth of the earth’s population and still growing in numbers, enduring for more than two millennia through many vicissitudes and much more fundamental menacing than this personal tragedy – should not be underestimated.Moreover, in the cause of transparency and indeed fairness to all, it is time for Cardinal O’Brien’s anonymous accusers to step forward into the public domain. If Catholicism in Scotland is to move on from this tragic affair a number of serious questions urgently require frank and honest answers from all concerned. The nation’s Catholics deserve nothing less.