Since there's been discussion about mortal sin and what it takes to commit one, I snipped a portion of a sermon from Fr. Wathen in 1990, the whole audio of the sermon is
here and can be downloaded to your desktop or phone if you want:
Our Lord in today’s Gospel speaks with a very few words of something most serious and it is truly a formidable message. He begins by saying: “Beware”, and we know very well what this means when someone says “beware”, he means to caution us against danger. When Our Lord says it, He is cautioning us with regard to nothing less than hell fire, the loss of our souls. When He says “beware”, He is putting us on our guard against a mortal danger.
And He says “beware of false prophets” and we understand therefore that there are two kinds, the true prophets and the false. The true prophets are not those who predict the future accurately, the prophet in the scriptures is not always one who does tell us what God has warned or God has revealed about the future. The prophet is mainly the spokesman for God, he is God’s mouth piece. And Our Lord here is saying that you are going to be confronted; He is saying this of course, not only for the ears of his listeners but for all generations afterward.
He is saying that ‘you are going to have to deal with false prophets as well as true ones’, and ‘you are going to have to distinguish between the two kinds’ and the reason he says beware, is because of the next line, that the false ones will come in the clothing of sheep. Which is to say they will appear as good as the true ones.
He is saying there will be a problem of distinguishing, and He is saying that the false prophets will have a very winning appearance, they will have the appeal and they will sound very knowledgeable, they will be likable and you will be taken with them. That is why there is a real danger here. It is not as if you could easily distinguish, on the very contrary.
I’m sure all of you have seen on television or heard on the radio enough protestant ministers to recognize that some of them are very personable; some of them give the impression of great learning. There is no doubt that they are likable. Someone must like them because someone, more than one someone, send them thousands and thousands of dollars to make sure that they continue, and therefore all these donors must be impressed.
There are two elements that must not be missed in this. The first is that the false prophets are deceivers. By their good appearance, by their affableness, and by the convincingness of their message they are a danger, and the other element is that people listen to them hungrily. Whatever they say, the people enjoy hearing.
Now this is the question.
Who is guilty? Is it the false prophet or is it those who listen?
If it is only the false prophet who is guilty, why is there any need to “beware”? Which is to say if God is not going to blame those who listen, those who are taken in by the falsehoods by the erroneous doctrine. The problem here is that you have heard all your lives that you cannot commit a mortal sin unless you have full knowledge and willingness, full consent.
Here Our Lord is saying you can be deceived, and you can listen and you can accept that which is erroneous, that which is deceptive, and if you do, even if you have good intentions, that is why there is danger. And Our Lord therefore says that being deceived is your fault. You can lose your soul by being deceived.
And He is saying your good intention is not enough because presumably, people do not listen to liars, deceivers or heretics, with a bad intention, or do they? – That is the question! They must! Because somewhere there is a sin, and the sin is in the evil in the heart.
Now we have to presume that sometime the heretical preacher has good intentions because he also is deceived, after all he learned his belief from some other false prophet and presumably he listened with what he thought was a good will, but he is deceived, and now he is passing his heresy and his scandal onto those who also are deceived.
We have to presume therefore that there is an evil will beneath the sincerity, which is to say those who give out with that which is erroneous; that which is false and that which is destructive, are guilty of doing it even if they imagine that they have good will.
And those who listen to that which is erroneous, you will remember that Our Lord uses the same expression in His parable, his allegory of the Good Shepherd, you remember that He says that the wolf enters among the sheep and he kills and he scatters. The wolf is the false teacher, the heretical preacher, the false prophet. And he introduces into the Church destruction and disunity because his doctrine is false there is bound to be disagreement among the Lord’s flock as what is the true doctrine and what is the false?