I believe this is a latin terminology, most generally used in law, which simply means 'utmost good faith'.
The Catholic Church appears now to be learning what this actually means. It is learning the lesson the hard way: dramatically falling attendances, disastrously declining income, failure to enrol for the priesthood at anything like an adequate standard, in short – the Church is in a deepening crisis. The moral authority of the Papacy has been sacrificed upon the altar of 'protected abuse'. I cannot see a time when this authority will be regained. The axe has been laid to the root of this tree..
But lets not be sectarian about this, other major religious institutions are also falling foul of the increased knowledge and 'self-determination' aspirations of the world population..
Judaism has become severely incapacitated by the less than reasonable behaviour of the Jewish State, Israel. The saying 'do unto others as you wish they would do to you' has been replaced by 'do unto others as was done to us'. The parallels between the politics of the Jewish State and the Nazis of World War 2 have become a despicable irony..
Iran's government does Islam no favours with it's reprehensible behaviour utilising religion as it's shield. Sharia law is generally perceived as being barbaric and not human. Nor do it's extremes speak to many people (with a choice to listen or ignore) of anything resembling a 'higher aspiration of the human spirit'. The Jihad movement's attempts to hijack Islam seem to be failing, yet there appears to be an undercurrent of progress and modernisation within Muslim populations that Islam has not yet grasped or seems incapable of responding to effectively. Alarmingly,for Islam, too many modern concepts of 'goodness' reveal the dysfunction of out-dated traditions.
Utmost faith; blind, unquestioning addiction to the institution is irrevocably being eroded by that other word in the title – good.
Mankind is progressing more rapidly in it's understandings and applicable definitions of 'good' than the religions. The moral high standards of the world society are applying judgements, theoretical and practical, to the behaviour of the high-powered and formerly unquestionably influential tenets of the religions.
If these religions are to survive the 21st century, they have to embrace a much larger definition of the word 'good'.
As for me, I have faith in the utmost good which is erupting from the mass of humanity. I happen to believe that the One God is responsible for it. In that I have utmost good faith.