'Believest' in the Bible

Jesus answered and said unto him, Because I said unto thee, I saw thee underneath the fig tree, believest thou? thou shalt see greater things than these.

and whosoever liveth and believeth on me shall never die. Believest thou this?

Believest thou not that I am in the Father, and the Father in me? the words that I say unto you I speak not from myself: but the Father abiding in me doeth his works.