For if you have trusted in Moses, you should have trusted me. Concerning me, the [famous] man has written.
Jhn 5:46 For had ye believed Moses, ye would have believed me: for he wrote of me.
Interesting and Hidden Aspects:
In the first phrase, Christ is saying that his opponents did not trust in Moses because they did not trust in Christ. In the previous verse, Christ was careful to avoid saying that his opponents trusted Moses (despite KJV translation) and instead said that they looked forward to him.
The verb translated as "you would have believed" is a little unusually. Normally, Christ uses the subjunctive mood to communicate the idea of something possibly happening, but here he uses the particle "an," which indicates a limited condition. It use almost requires the previous conditional "if" phrase though the "if" is left out of the KJV version.
Interestingly, Christ uses the term ekeinos to refer to Moses, which is simply translated as "he" in the KJV. However, this word is used to highlight a person or idea previously mentioned. Jesus often uses it to highlight an actions ("in that manner") but the word is often used to refer to famous people in the past, as it is here. Christ is using it to highlight the importance of Moses to the Jews.
εἰ Untranslated is ei, which is the particle used to express conditions "if" (implying nothing about its fulfillment) or indirect questions, "whether." It also means "if ever", "in case," and "whenever." It is combined with various conjunctions to create derivative conditions.
ἐπιστεύετε (2nd pl imperf ind act) "Had ye believed" is from pisteuô (pisteuo), which means "to trust, put faith in, or rely on a person", "to believe in someone's words", "to comply", "to feel confident in a thing," and "to entrust in a thing."
ἐπιστεύετε (2nd pl imperf ind act) "Ye...have believed" is from pisteuô (pisteuo), which means "to trust, put faith in, or rely on a person", "to believe in someone's words", "to comply", "to feel confident in a thing," and "to entrust in a thing."
ἂν "Would" is from an, which is a particle used with verbs to indicate that the action is limited by circumstances or defined by conditions. There is no exact equivalent in English, but it is translated as "possibly," "would have", "might", "should," and "could."
ἔγραψεν (3rd sg aor ind act ) "Wrote" is from graphê (grapho), which means "representing by means of lines", "a drawing", "writing", "the art of writing," and "that which is written." It came to mean "scripture" from its use in the Gospels.