After mentioning deceivers, the elder says, “Watch yourselves” (2 John 1:8). He gives the reason: “so that you may not lose what we have worked for, but may win a full reward” (2 John 1:8). The warning is connected to protecting the community from the effects of false teaching (2 John 1:7–8).
In 2 John 1:8–9 the writer urges the readers to stay alert about themselves so that what has been achieved is not lost and so that a “full reward” is received. He then draws a sharp line: the person who goes beyond the teaching about Christ and does not stay within it is described as not having God. These verses come after the letter’s warning that “many deceivers” have gone out into the world, especially those who do not acknowledge Jesus Christ as coming in the flesh (2 John 1:7).
These verses assume that a Christian community can build real progress that is worth guarding. The danger is not only outside “deceivers” (verse 7) but also internal drift: the readers can “lose” what has been accomplished if they stop paying attention (verse 8).
A common mistake is to turn the wording into a slogan. The better reading keeps the phrase tied to the passage, the speaker, and the problem the book is addressing.
Start with 2 John 1:8, then read the surrounding section so the answer stays connected to the passage's flow.
8Watch yourselves, that we don`t lose the things which we have accomplished, but that we receive a full reward.