What are heresies?
Not a modern problem, and not just a word for “beliefs I personally dislike.” A heresy is a teaching that denies something essential to the actual Christian gospel — and Scripture itself names and confronts specific ones within the first generation of the church.
Heresy isn’t new — Scripture names it directly
Long before “heresy” became a churchy-sounding word, the apostles were already writing directly against specific false teachings circulating in the earliest churches.
“For many deceivers have gone out into the world, those who do not confess the coming of Jesus Christ in the flesh. Such a one is the deceiver and the antichrist.”
John is confronting an early teaching (often called docetism) that treated Jesus as only appearing human — a spirit merely looking like flesh, never really one of us. His response isn’t gentle disagreement; he calls it deception.
“See to it that no one takes you captive by philosophy and empty deceit, according to human tradition, according to the elemental spirits of the world, and not according to Christ.”
Paul confronts an early mystical philosophy (with elements later associated with Gnosticism) claiming secret spiritual knowledge beyond what Christ himself revealed, along with an unhealthy fixation on angels (Colossians 2:18).
“I marvel that you are turning away so soon from him who called you in the grace of Christ and are turning to a different gospel… But even if we or an angel from heaven should preach to you a gospel contrary to the one we preached to you, let him be accursed.”
Here Paul confronts teachers (often called Judaizers) insisting Gentile Christians had to keep the Jewish law to be truly saved — adding a requirement to grace alone. Paul’s language for it is about as severe as language gets.
Why doctrine matters this much
This isn’t Paul being needlessly harsh about minor disagreements. Scripture treats getting the essentials right as a matter with real weight.
“Keep a close watch on yourself and on the teaching. Persist in this, for by so doing you will save both yourself and your hearers.”
“He must hold firm to the trustworthy word as taught, so that he may be able to give instruction in sound doctrine and also to rebuke those who contradict it.”
Paul ties Timothy’s own teaching directly to the eternal outcome of the people listening to him. Doctrine, in Scripture’s own view, isn’t abstract theological hobby-horsing — it’s the difference between a message that actually saves and one that doesn’t.
The essential doctrines you cannot get wrong
A handful of doctrines sit in the “essential” tier from the framework in the previous article — deny these, and whatever a group calls itself, it isn’t teaching the historic Christian faith.
The Trinity
What Scripture teaches: one God, eternally existing in three distinct persons — Father, Son, and Holy Spirit — each fully God, sharing one being.
Jesus, fully God and fully man
What Scripture teaches: one person, genuinely and completely God, genuinely and completely human — not a blend or a percentage of each.
Jesus’s bodily resurrection
What Scripture teaches: Jesus genuinely died, was buried, and was bodily raised — not a substitution, not a swoon, not a spiritual-only rising.
Worth noticing: the earliest counter-story to the resurrection, from Jesus’s own opponents, wasn’t “he never really died” — it was that his body had been stolen.
“Tell people, ‘His disciples came by night and stole him away while we were asleep.'”
A stolen-body story only makes sense if there was a body, in a tomb, that was genuinely gone — which indirectly confirms the very thing it was trying to explain away: Jesus had actually died, and the tomb was actually empty.
The doctrine of sin
What Scripture teaches: sin is a real, personal offense against a holy God — not a lapse in memory or a minor rule broken — and it carries a real, deserved penalty.
“For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.”
If sin is redefined as something smaller than this, the rest of the gospel stops making sense — there’s no real reason Christ would need to die for a mere lapse of memory.
How do you tell if a church is genuinely legitimate?
Two starting steps: look at its actual doctrine — a real statement of faith, not just warm language — and specifically how it answers who Jesus is. A group that’s vague or evasive about Christ’s full deity and humanity is worth real caution.
But it’s rarely that simple from the outside, and Scripture warns about exactly this difficulty.
“Beware of false prophets, who come to you in sheep’s clothing but inwardly are ravenous wolves.”
Groups that function as cults rarely announce themselves as such. Two further practical questions help:
- Extra authority?Does the group claim another book, prophet, or ongoing revelation as equal to or higher than the Bible — something the Bible itself must be read through, rather than tested against?
- Internal consistency?Does the teaching hold together, or does it quietly shift and contradict itself depending on who’s asking, or what’s convenient?
Can you believe the “Jesus” a cult preaches and still be saved?
This is really the question underneath everything above, and it’s worth walking through directly rather than leaving abstract. If a group teaches that Jesus wasn’t truly human, ask the obvious follow-up: how could he have died a real human death, for real human sin? A death that wasn’t genuinely human can’t accomplish what Scripture says the cross accomplished. If a group teaches that Jesus was a created being rather than fully God, ask: could a finite, created life actually pay an infinite debt owed to an infinite God? Scripture’s answer, throughout this whole site, has been no.
Trusting sincerely in a “Jesus” who isn’t the one Scripture actually describes doesn’t secure the salvation the real Jesus provides — it secures trust in someone who was never able to provide it, however familiar the name sounds.
A quick reference: 8 heresies through history
Most doctrinal errors that show up today are old ones wearing new names. Here are eight of the most historically significant, several of which map closely onto groups active today.
Arianism
Taught that Jesus was God’s first and greatest created being — not eternally God himself. Formally condemned at the Council of Nicaea, 325 AD.
Modern parallel: Jehovah’s Witnesses teach that Jesus is Michael the archangel, created by God before all else — a position historians of doctrine describe as Arian in substance.
Modalism (Sabellianism)
Taught that Father, Son, and Spirit are not three distinct persons but one person appearing in three successive roles or “modes.” Condemned in the early third century.
Modern parallel: Oneness Pentecostal churches teach a similar view, denying three distinct, eternally co-existing persons.
Docetism
Taught that Jesus only appeared human — a spirit merely wearing the look of flesh, never truly incarnate. Confronted directly in 2 John 1:7.
If Jesus wasn’t genuinely human, he couldn’t have died a genuinely human death for human sin.
Gnosticism
Taught salvation through secret spiritual knowledge available only to an enlightened few, often paired with the idea that physical matter itself is inferior or evil. Confronted in Colossians 2:8, 18.
Undermines grace through faith by making salvation depend on hidden knowledge instead.
Tritheism
Treats Father, Son, and Spirit as three entirely separate gods, rather than three persons sharing one divine being — the opposite error from modalism.
Modern parallel: Latter-day Saint (Mormon) theology teaches the Father, Son, and Holy Ghost are three distinct beings/gods, not one God in three persons — alongside its own further, distinct claims that God the Father was once a mortal man who progressed to godhood, and that faithful humans may become gods themselves.
Pelagianism
Taught that humans aren’t fundamentally corrupted by sin and can achieve righteousness before God through their own moral effort, without needing grace. Opposed by Augustine.
Reduces the gospel to self-improvement rather than rescue.
Nestorianism
Taught that Christ’s divine and human natures were so distinct they amounted to two separate persons loosely joined together, rather than one unified person.
Addressed at the Council of Ephesus, 431 AD.
Eutychianism (Monophysitism)
The opposite error from Nestorianism: taught that Christ’s divine and human natures blended into a single new, hybrid nature, rather than remaining fully distinct within one person.
Addressed at the Council of Chalcedon, 451 AD, which defined Christ as one person in two natures, “without confusion, without change, without division, without separation.”
A note on tone: naming what a group actually teaches is different from mocking the people who believe it — many are sincere, and some are family or friends worth engaging with patience and respect, even while being honest about where the actual teaching departs from historic Christian faith.
Hard questions
Isn’t calling something “heresy” just an unloving way to shut down disagreement?
It can be misused that way, and Christians should be careful never to fling the word at genuine secondary or important-conviction disagreements. But used correctly, it names something specific and testable — a denial of an essential doctrine — not simply “a view I dislike.”
What if I’ve genuinely believed some of these errors without realizing it?
Sincerely misunderstanding a doctrine, especially something as genuinely difficult as the Trinity, is different from deliberately teaching a denial of it. This is exactly what honest correction and continued learning are for — no one arrives at full theological precision instantly, and Scripture itself calls believers to keep growing in understanding.
Where can I actually check a church’s doctrine before getting involved?
Ask directly for its statement of faith, and read how it answers who Jesus is, what the gospel is, and whether Scripture alone is its final authority. A healthy church will welcome that question rather than deflect it.
A closely related question sits right next door.
My Christian Friend Differs From Me — Is One of Us Wrong? →