Father Pfeiffer, in a sermon, was talking about the gospel where it says, and I paraphrase: a good fruit cannot bring forth evil fruit but only good fruit and an evil tree cannot bring forth good fruit but only evil fruit.
I do not understand what this means. It does not make sense because the elect who are the good trees commit many sins and the reprobate who are the bad trees commit many acts that are good. If he is not talking about deeds, then what is he talking about? Can someone who knows more explain it to me?
I'm not a teacher. Take this as humble counsel from fellow laity, and not teaching. I recommend Aquinas's work.
Galatians 5
16I say then, walk in the spirit, and you shall not fulfil the lusts of the flesh. 17For the flesh lusteth against the spirit: and the spirit against the flesh; for these are contrary one to another: so that you do not the things that you would. 18But if you are led by the spirit, you are not under the law. 19Now the works of the flesh are manifest, which are fornication, uncleanness, immodesty, luxury, 20Idolatry, witchcrafts, enmities, contentions, emulations, wraths, quarrels, dissensions, sects, 21Envies, murders, drunkenness, revellings, and such like. Of the which I foretell you, as I have foretold to you, that they who do such things shall not obtain the kingdom of God. 22
But the fruit of the Spirit is, charity, joy, peace, patience, benignity, goodness, longanimity, 23Mildness, faith, modesty, continency, chastity. Against such there is no law. 24And they that are Christ's, have crucified their flesh, with the vices and concupiscences.25If we live in the Spirit, let us also walk in the Spirit. 26Let us not be made desirous of vain glory, provoking one another, envying on another.
Only those of us with God's Spirit can bring forth fruit of the Spirit.
For instance, the fruit of the Spirit that is peace is different from the world's peace. People without God's Spirit can have peace, but His peace is not as the world gives.
Peace I leave with you, my peace I give unto you: not as the world giveth, do I give unto you. Let not your heart be troubled, nor let it be afraid.
John 14:27
Galatians 6:8
For what things a man shall sow, those also shall he reap. For he that soweth in his flesh, of the flesh also shall reap corruption. But he that soweth in the spirit, of the spirit shall reap life everlasting.
Our Blessed LORD said:
Either make the tree good and its fruit good: or make the tree evil, and its fruit evil. For by the fruit the tree is known.
So while we sin, we do not continue in sin willfully. We should not be committing mortal sins regularly, although if we do we can obtain mercy through God's grace (perfect contrition, if possible through His grace, and then confession). If we continue in sin willfully, there remains no sacrifice for sin (read Hebrews). Sin separates us from God. Even venial sins weaken us and hurt our charity (LOVE - God is Love).
Those who are not among the faithful will always bring forth evil fruit. Even if sometimes, by God's grace, they are able to love and do good works, their tree is corrupt and can not be good without God's sanctifying grace.
Remember, He said "not as the world gives."
Sow in the Spirit. Pray without ceasing, increase in knowledge and in virtue, and fear the LORD. Fear of the LORD keeps evil at bay.
God is Love. God's Love is not the same as the world's love. There is a false light. Satan masquerades as an angel of light.
I hope this helped. Like I said, I am not a teacher, but iron sharpens iron. Seek counsel from your spiritual adviser.
Check out some of St. Aquinas's work.
If anyone finds error in what I say, please correct me.
Peace in Christ