John 3:12-15

If I told you earthly things [that is, things that happen right here on earth] and you do not believe, how will you believe and trust Me if I tell you heavenly things? No one has gone up into heaven, but there is One who came down from heaven, the Son of Man [Himself—whose home is in heaven]. Just as Moses lifted up the [bronze] serpent in the desert [on a pole], so must the Son of Man be lifted up [on the cross], [Num 21:9] so that whoever believes will in Him have eternal life [after physical death, and will actually live forever].