Believe me does not mean “put your faith in me,” but “believe what I am going to say to you” (note New English Bible “Believe me when I say that…”; and Jerusalem Bible “You must believe me when I say…”).

The rendering of I am in the Father and the Father is in me should reflect the rendering of this same expression in verse 10.

Believe because of the things I do is literally “believe because of the works themselves.” Some Greek manuscripts supply “me” after believe, as in the first part of this verse. The Greek manuscript evidence is against the inclusion of “me” here, but it may be required translationally. Several translations (for example, Revised Standard Version, Phillips, Die Bibel im heutigen Deutsch) do include “me,” but probably on translational grounds. Note, for example, Die Bibel im heutigen Deutsch “Believe me: the Father and I are one. If you will not believe because of my word, then believe me because of these deeds.” Jerusalem Bible includes the pronoun “it” as the object of “believe,” accomplishing essentially the same purpose: “believe it on the evidence of this work, if for no other reason.” (“It” refers to the statement “that I am in the Father and the Father is in me.”) New English Bible supplies an object for “believe” by rendering “or else accept the evidence of the deeds themselves.” Either meaning, “believe me when I say” or “believe what I say,” is faithful to the context. The point is that the verse should not be so translated as to indicate that “believe” here refers to belief in Jesus in the ordinary sense of the word. The appeal is to believe the truth of what he says, best expressed in many languages by “believe me when I say.”

The ellipsis in the condition If not must often be filled out, for example, “If you do not believe what I say” or “If you do not believe just because of what I say.” This second rendering fits well with the following clause, “believe because of what I have done” or even “… what my Father has done through me.”

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 .