Who Wrote 1 John?

I was surprised to learn that there is no internal proof that the apostle John wrote this epistle.

Then again, John refers to himself not by name, but by the phrase "The disciple whom Jesus loved" in his gospel. There is a humility and an element of mystery in this practice.

I wonder why John refers to himself by name in Revelation but not in his other four books?

The following early church historians name John the author of 1 John, according to the Commentary Critical and Explanatory on the Whole Bible:

Polycarp
Eusebius
Irenaeus
Clement of Alexandria
Tertullian
Cyprian

Just digging more deeply into the primary sources written by these authors could become a lifetime of work.

In the same way that a good scientist accepts the conclusions of peer review as authoritative until proven otherwise, it is reasonable to accept John's authorship of this letter.

Additionally, there are many parallels between the gospel of John and this letter. The EasyEnglish Bible Version and Commentary is just one place that outlines these similarities clearly and thoroughly.