Why was the Roman Catholic Empire so Afraid of the "Gnostics"?

The Roman Catholic Empire actively suppressed and persecuted "Gnostic heretics" because they challenged church doctrine/ authority.

Gnostics believed salvation was personal and spiritual (invisible, attained by faith), not dependent on bishops, priests, or sacraments.
The fake church, which was becoming more structured, saw this as dangerous and divisive.

Christian leaders like Irenaeus (Against Heresies, ~180 AD) and Tertullian wrote attacks against Gnosticism.
Gnostic teachers like were excommunicated.
The Church destroyed many Gnostic writings.

Emperor Constantine made Christianity legal (Edict of Milan, 313 AD) and supported Nicene Christianity, rejecting Gnostic groups.
Theodosius I (late 4th century) declared Gnostic sects illegal under Roman law.
Gnostic texts were burned, churches were shut down, and followers were executed, massacred or forced to convert.

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