Jesus claimed to be the Messiah, but this claim was rejected by Jewish leadership… yet Nicodemus (one of said leaders) visited Jesus under cover of darkness and pressed him further.
Read 16-21 again, remembering who Nicodemus was and that he did not visit openly, but secretly in the darkness, and that his line of questioning was patronizing at best, and bad faith at worst (which Jesus does not let him get away with).