Any honest historian or enthusiast for Church history will tell you that there is no “golden age” of the Church; never has been and there never will be until Christ comes in His glory. This is because the Church is a reflection, an oftentimes very imperfect reflection, of the age to come.
There have been abuses, heresies, reforms, etc., etc., etc., throughout the long history of the Church. Sexual immorality among both laity and clergy, drunkenness, liturgical abuse, etc., have been around at least since the time of St. Paul. He wrote against such things in his letters, especially his letter to the Corinthians.
The earliest Ecumenical Councils were convened not only to correct heresy, but also to correct abusive and/or self-destructive behavior among both clergy and laity. And if you’ve ever read any of the documents of any of the Lateran Councils, particularly Lateran IV (around the time of Sts. Thomas Aquinas and Bonaventure), you’ll realize that those Councils weren’t so much about dogma as they were discipline among the clergy.
Most of the saints that we honor didn’t live in peaceful times within the Church. Sts. Francis and Clare of Assisi, St. Bernard of Clairvaux, St. Catherine of Sienna, Sts. John of the Cross and Teresa of Avila, etc., etc., etc. were all very avid and outspoken reformers of the Church. They spoke boldly yet charitably against the abuses that existed in their day. St. Augustine himself combatted the heresy of Pelagianism (although sometimes went to the opposite extreme), and St. Dominic founded his great Order to combat the Albigensian heresy of his day.
I tend to agree with the likes of Fr. Robert Taft, S.J. There is no “golden age” of the Church, save for the age in which we live now. By this he means, there’s no point in daydreaming about the past and longing for an elusive “golden age.” Our lot is to make the best of the age in which we live, just as the saints of old have done throughout the history of the Church.
