John 15:5

Ver. 5. “ I am the vine, you are the branches; he who abides in me and I in him, this one bears much fruit; for apart from me, you can do nothing. ”

Jesus begins by summarily reaffirming the nature of the relation. While contemplating the natural vine which He has before His eyes, He recognizes in it the image of the complete dependence on Him in which His disciples are: “Yes, here indeed is what I am to you and what you are to me: I, the vine; you, the branches! Do not therefore allow yourselves ever to fall into the temptation of making yourselves the vine, by desiring to derive anything from yourselves.” The meaning is, therefore: “In me, rich fruitfulness; apart from me, barrenness.” If this second idea is given as a proof of the first (ὅτι, because), it appears at the first glance scarcely logical. But if Christ is so completely everything that the believer can do nothing without Him, does it not follow that the latter can do much, so long as he shall remain united with Him?

Then, in John 15:6, the fate of the branch which has become unfruitful, and in John 15:7-8, the fate of the branch united with Christ and fruitful in Him.