The General Instructions for the Mass (the "GIRM") instruct the priest to give a homily on all Sundays and Holy days. It says that the homily is to be an explanation of the texts of Scripture in the readings for the day. This means that the priest is not just to talk about whatever is on his mind that day (or worse, what he read in the newspaper -- yes, I have heard about this happening). The homily is not a running personal opinion time. It does not matter one tiny bit what the priest's opinion is; when we take our vows as a priest we promise to teach the Word of God and not our own ideas.
There are "homily helps" that you can find online that help to guide a priest in the preparation of his homily. It is a common occurrence on certain holy days that most of the laity are unaware of for these to be sent out. These are most commonly distributed to priests who serve parishes whenever an upcoming holy day is going to have a special character to it. Essentially, the "homily helps" tell the priest "here is how to preach on this particular subject from the given passages". There is a significant problem with this practice.
Firstly, if the passage is not already evidently showing the particular subject, then inserting the idea into the passage because of some vague word association is not faithful to the text. We cannot merely "squeeze" a truth into the wrong place. Just because it is true that our God is triune, does not mean that we can force the doctrine of the trinity onto any passage we wish to. This is not only unfaithful to Scripture, it is unfaithful to the people of God to be told that God is saying something that He is not actually saying in that particular text. If the text is already referring to the desired subject, the priest does not need "homily helps", and if the passage is not already referring to it, we should not pretend that it is.
Secondly, this habit is encouraging us to project our own ideas on to a text of Scripture (and that is never a good thing). Proper explanation of a passage of Scripture is called "exegesis" (which means to bring out of the words their proper meaning). This habit of "here's how to preach on this subject with this text" is often the exact opposite. To "insert" one's own idea into the text is called "eisegesis" (which means to add into the words a meaning you want to have there). Having been a protestant for years, I saw an overabundance of "eisegesis"; the ideas inserted into the texts of Scripture by most protestants were sometimes staggering as to how self-serving these things were.
Having been a protestant minister for 16 years, and now a Catholic priest for the last 8 years, I can say that I have never read a "homily help" that was treating the text fairly. It would be much better just to have the priest say: "I'm not going to comment on the text today, because we have an important subject to deal with. Today I'm going to speak about . . . " He is certainly not "explaining the text" as the GIRM says to do, but at least he is not pretending to do so.
I have heard quite a few people tell me about having listened to homilies that were--shall we say--less than helpful to their faith. Insisting that they do not give me names (I absolutely do not want to know who they are talking about), I will frequently ask what was wrong with the homily that they were complaining about. I can summarize all the problems referred to by two simple example statements that were given to me recently. First, "the priest just rambled on and on and I had no idea what he was talking about", and second, "he explained some philosophical concept that went over everyone's head".
This does seem to be what happens so frequently these days. Often the text is not explained, but only referred to in a vague manner. It is common for the homily to sound about as exciting as reading the ingredients list on a candy bar. The people of God should never be bored by the preaching of the Word of God. The word of God is "living and active" (Heb 4:12) and should be presented to the faithful as such. The priest should tell the people what the Word of God says and help them apply it to their lives. It is a simple process, but not everyone is gifted to do this (and Bishops should not consider this a small issue).
If the seminaries gave better preparation and training on how to interpret the text according to Catholic teaching as well as on how to explain the Scriptures to a varied group of the faithful, then we would not have the need for "homily helps". The "help" will have already come in the preparation; my grandmother used to say "an ounce of prevention is worth a pound of cure". The consequences for God's faithful are more than I can tell you here but they are worth the extra work. People, please pray for your priests; every single day.
