In Greek this statement also is conditional (beginning with “but if”). However, the condition is so stated as to assume that the Jews did not believe what Moses wrote, and so Good News Translation renders But since you do not believe. Goodspeed indicates it by “But if you refuse to believe….”

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 .