For I write this to you, compare comments on verse 21; this refers back to verses 18-25.

Those who would deceive you is in the Greek a participle in the present tense. This tense serves here to indicate the continuing attempt of the deceivers. This is brought out in Good News Translation‘s “who are trying to deceive you.” For the verb see comments on the reflexive form “we deceive ourselves” in 1.8.

The result of you being deceived or being led astray may be that they sin. Therefore some versions render “to deceive” by ‘to cause to be guilty,’ ‘to entice to sin.’ This is unadvisable, since it is saying more than John says or seems to imply.

Quoted with permission from Haas, C., de Jonge, M. and Swellengrebel, J.L. A Handbook on The First Letter of John. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .