And we are writing this, namely, ‘to you,’ which may have to be added for reasons of idiom. The Greek present tense can better be rendered simply by “we write” (King James Version, New English Bible [New English Bible], Good News Translation). The connective “And” has resultative force here and may be rendered by ‘Therefore’ or ‘So.’
The plural pronoun we is confusing in some languages, because it is after all one person who is writing, though as the representative of many eyewitnesses. Some versions therefore have to shift to the first person singular.
This refers to the message of the letter as a whole rather than to a specific item in what directly precedes or follows.
† The reference of the verb are writing is to the fact rather than to the manner of communication, to information rather than to the actual tracing of a series of characters. For this reason some versions use a verb meaning ‘to tell,’ ‘to inform of,’ ‘to communicate.’ The same holds true in the other occurrences of the verb in 2.1, 7-8, 12-14, 21, 26; 2 John 5, 12; 3 John 9, 13.
In that our joy may be complete (or ‘so that we may have complete joy,’ ‘so that we may rejoice fully/completely’), the conjunction that refers to intended result again.
Our is given inclusive force in some versions, but it is more in line with the structure of verses 1-4 to take it as exclusive, referring to the group of eyewitnesses only, not including the persons addressed. The clause indicates that the joy the eyewitnesses have because of their fellowship with God through Christ can be complete only when other Christians share that fellowship.
† Joy, or ‘gladness,’ is an important Johannine term; compare, for example, John 15.11; 16.20, 22, 24; 17.13. In these Letters it occurs also in 2 John 12; 3 John 4; compare also “rejoice” in 2 John 4; 3 John 3. Receptor languages often possess one specific term for the concept but sometimes express it by an idiomatic phrase such as ‘happiness of life,’ ‘warmth (or smiling, or good feeling) of heart,’ ‘the being lifted up of the heart,’ ‘the good taste of one’s heart,’ ‘the spirit being made sweet,’ ‘a song in the stomach,’ ‘having a sweet (or wide open) liver,’ ‘expansion of the inner-being.’
† Complete is in the Greek literally “filled,” then, “full.” The same term occurs in 2 John 12. It expresses that the joy will lack nothing, that it will fill their hearts to the brim. The term refers to the highest degree: they will be as glad as they possibly can be.
The concept, of course, can be expressed in different ways, dependent on the specific idiom used for joy; compare, for example, ‘that our hearts may be lifted up to the highest point.’ In one language, where fullness of joy is associated with tranquillity, the clause is rendered by ‘that our hearts may sit down.’ In another language one says ‘that joy may be equal to our minds.’
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 .