Your father is obviously a reference to the Devil, (verse 44), but it is better not to make this information explicit until it is done so in the Greek text.

Good News Translation inverts the order of the last two clauses of this verse. God himself is the only Father we have is obviously the meaning of the Greek “we have one Father, God.” New English Bible translates “God is our father, and God alone.” One may also render this expression “our only father is God” or “God alone is our father” or “we do not have another father; God is our father.”

We are his true sons is literally “We were not born of fornication.” Since the word “fornication” is not commonly used in English, Good News Translation and most other modern translations avoid its use. The force of what these Jews are saying is expressed vividly by Moffatt, “We are no bastards.” Phillips is also accurate, “We are not illegitimate”; New American Bible has “We are not illegitimate breed!” Jerusalem Bible translates “We were not born of prostitution.” It is difficult to imagine men in the heat of argument saying “We are not base-born” (New English Bible). Good News Translation simply changes the Greek negative statement (“We are not…”) into a positive one (We are his true sons). One may also say “We are his real sons.” In expressing the statement negatively, some languages may employ an idiom. Instead of “We are not bastards,” they may say “We are not secret children” (that is, children that one doesn’t speak about). Other languages may have such expressions as “We are not refused children” or “We are not children from other women.”

These antagonists may be making an insinuation about Jesus himself; in affirming that they are not illegitimate, they may be suggesting that he is. In the Greek clause “We were not born of fornication” the pronoun we is emphatic, suggesting a contrast between themselves and Jesus. (“We were not born of fornication, but you were.”) Many commentators tend to feel that such a barb is intended.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .