As you have acknowledged, the Church on Earth is made up of human beings—in other words, sinners. Sinful behavior (sexual abuse by priests, for example) therefore can have no bearing on the authority of the Church to teach infallibly. Why is that? Because Christ founded the Church and through the Apostles and their successors, meant for it to continue in order to bring men to salvation. He knew his Church would be made up of sinners. And yet about his Church He said “…thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose on earth, it shall be loosed also in heaven.” (Matthew 16:18-19)
In order for the Church to bind in heaven, it must teach the truth. In order for this to be assured, Christ sent the Holy Spirit, promising the Apostles (that is, the Church):“But when he, the Spirit of truth, is come, he will teach you all truth.” (John 16:13)
Infallibility in the Church does not mean sinlessness. It is the action of the Holy Spirit preventing the Church from teaching error in faith or morals. You will find
this article helpful.
Regarding biblical interpretation, the Catechism teaches:
111 But since Sacred Scripture is inspired, there is another and no less important principle of correct interpretation, without which Scripture would remain a dead letter. “Sacred Scripture must be read and interpreted in the light of the same Spirit by whom it was written.”
This is the same Holy Spirit who guides the Church into all truth. It therefore makes sense to look to the Church as the proper interpreter of Sacred Scripture.
Finally, a little about indulgences from
this helpful article: The definition of indulgences presupposes that forgiveness has already taken place: “An indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven” (
Indulgentarium Doctrina norm 1). Indulgences in no way forgive sins. They deal only with punishments left after sins have been forgiven.
This comes under “binding and loosing.” I take seriously the indulgence printed in the front of my bible granted for reading Sacred Scripture.One never could “buy” indulgences. The financial scandal around indulgences, the scandal that gave Martin Luther an excuse for his heterodoxy, involved alms-indulgences in which the giving of alms to some charitable fund or foundation was used as the occasion to grant the indulgence. There was no outright selling of indulgences. The Catholic Encyclopedia states: "
t is easy to see how abuses crept in. Among the good works which might be encouraged by being made the condition of an indulgence, almsgiving would naturally hold a conspicuous place. . . It is well to observe that in these purposes there is nothing essentially evil. To give money to God or to the poor is a praiseworthy act, and, when it is done from right motives, it will surely not go unrewarded."
Thank you - quite helpful. I’ll read the articles.
Brian