John 3:2 He came to Jesus at night and said, “Rabbi, we know that you are a teacher who has come from God. For no one could perform the signs you are doing if God were not with him.”
Nicodemus was a member of the Jewish council and as such would have upheld the laws as recounted by Moses so many years ago – but He also saw something in what Jesus did!
If it were not for what He saw Jesus do, he would have continued to struggle in believing a man could call himself the Messiah.
He saw what Jesus did and he knew there was no way a mere man could do such things without God being totally behind him. So He believed Jesus!