Matthew 7:15–20

Matthew 7:15 — The Disguise of the False Prophet Jesus opens with the imperative prosechete ("Beware" / "Pay attention"), a word of urgent, active vigilance. The image of sheep's clothing (en endymasin probatōn) is pointed: false prophets do not announce themselves as enemies. They adopt the visible markers of belonging — the vocabulary of faith, the posture of piety, the appearance of pastoral care. The phrase "ravening wolves" (lykoi harpages) echoes Ezekiel 22:27, where corrupt rulers are described as wolves tearing prey. The danger is not the wolf who attacks from outside but the one already within the fold, moving among the sheep. Origen notes that this is precisely what makes such figures so deadly: they exploit the trust that the community of faith naturally extends to those who appear to share its identity.

Verse 16a — The Principle of Discernment "By their fruits you will know them" (apo tōn karpōn autōn epignōsesthe autous) introduces the epistemological method Jesus endorses. The verb epignōsesthe carries the force of full, experiential recognition — not superficial or instant, but knowledge born of sustained observation. Jesus does not say "by their doctrines alone" or "by their claims." The fruits (karpoi) in view include both the moral life of the teacher and the spiritual condition of those formed under their influence. A teacher who produces anxiety, pride, division, or licentiousness in their followers bears bad fruit regardless of the sophistication of their theology.

Verse 16b — The Rhetorical Questions The two questions about grapes and figs are drawn from the agricultural world of Galilee and carry instant intuitive force. Thorns and thistles (akanthōn and tribōlōn) were familiar images of cursedness from Genesis 3:18, where they emerge as consequences of the Fall. Jesus subtly invokes the moral disorder at the root of false prophecy: it is connected to the disordering of creation by sin. A thornbush cannot produce a grape because its nature is different; similarly, a soul disordered by pride, ambition, or self-deception cannot ultimately produce the fruits of the Holy Spirit (Gal 5:22–23).

Verses 17–18 — The Tree and Its Nature Jesus elaborates the principle with formal symmetry: good tree/good fruit, corrupt tree/evil fruit — and then states the impossibility of reversal. The word translated "corrupt" (sapron) means rotten or decayed — not merely weak or undeveloped, but fundamentally compromised in its inner constitution. This is not a counsel of despair about the possibility of conversion, but a statement about the reliable correspondence between interior disposition and exterior fruit. Augustine, in De Doctrina Christiana, draws on this passage to argue that the interpreter of Scripture must themselves be formed in charity, or their reading will be distorted: sapron interiority produces distorted interpretation.

Matthew 7:19 — Eschatological Consequence The image of the tree cut down and thrown into fire appears nearly verbatim in John the Baptist's preaching (Matt 3:10), creating a deliberate echo. Jesus is not softening the Baptist's eschatological urgency; He is relocating it — from the crowds generally to those who claim prophetic authority in particular. The eschatological stakes for teachers are higher than for ordinary disciples (cf. James 3:1). This verse anchors the entire passage in final judgment: discernment is not merely pragmatic but a preparation for the accounting each soul will make before God.

Matthew 7:20 — The Closing Verdict The repetition of verse 16a creates a literary inclusion (inclusio), framing the intervening teaching as an explanation of one overarching principle. The closing restatement is deliberate: Jesus wants this criterion — fruit, not claim; life, not title — to be memorable, portable, and actionable. It is, in effect, a hermeneutical key for navigating every subsequent encounter with teachers, movements, and spiritual authorities throughout the life of the Church.

Catholic tradition brings several distinctive lenses to this passage that deepen its meaning considerably.

The Church's Prophetic Office and Its Boundaries. The Catechism teaches that the whole People of God participates in Christ's prophetic office (CCC §785), meaning that true prophecy — in the broad sense of bearing witness to God's word — belongs to every baptized Christian. But this same tradition, precisely because it takes prophecy seriously, insists on rigorous discernment. The First Letter of John commands "testing the spirits" (1 John 4:1), and the Catechism explicitly states that charisms "must be subject to the authority of the Church's pastors" (CCC §801). This passage in Matthew is one of the scriptural warrants for that institutional responsibility.

The Fathers on Interior Moral Corruption. John Chrysostom (Homilies on Matthew, Homily 23) identifies the false prophets here with teachers who flatter their audiences, accommodating the Gospel to what people want to hear rather than what they need. He notes the particular danger of eloquence divorced from holiness. Jerome, commenting on this passage, warns that the capacity to cite Scripture is not itself a fruit — the demons know Scripture too (cf. Matt 4:6).

The Criterion of Sanctity. Pope Benedict XVI, in Jesus of Nazareth (Vol. 1), reflects on the Sermon on the Mount as a portrait of the inner logic of Christ's own life. From this perspective, the "good fruit" Jesus describes is ultimately participation in His own charity — the agape that the Holy Spirit pours into redeemed hearts (Rom 5:5). True prophecy is inseparable from holiness; the saint is, in the deepest sense, the true prophet.

Magisterium and Discernment of Movements. The Second Vatican Council's Lumen Gentium §12 affirms genuine charisms in the Church while insisting on their judgment by those who preside, so that authentic gifts are not extinguished nor false ones tolerated. This conciliar teaching gives institutional flesh to Jesus' instruction here.

For a Catholic today, this passage is not merely a warning about exotic cult leaders or distant heretics. It addresses every formation choice a Catholic makes: which podcasts, which spiritual directors, which authors, which online voices, which movements shape their interior life. The contemporary Catholic information ecosystem is dense with teachers claiming prophetic or spiritual authority, and Jesus' criterion — fruit, observed over time — is more relevant than ever.

Practically, this means asking: Does following this teacher make me more humble, more charitable, more rooted in the sacraments, more integrated in my parish community? Or does it produce spiritual pride, contempt for the Church's ordinary life, dependence on the teacher's personality, or anxiety? Does this movement build up the Body of Christ, or does it slowly separate me from it? The fruit criterion requires patience — thorns do not produce grapes immediately, and neither do false prophets immediately reveal themselves. It demands sustained, prayerful observation, cultivated through regular examination of conscience, spiritual direction, and attentiveness to the testimony of trustworthy witnesses.