What does John 14:19-20 mean?

19 Yet a little while, and the world seeth me no more; but ye see me: because I live, ye shall live also. 20 At that day ye shall know that I am in my Father, and ye in me, and I in you. (John 14:19-20 KJV)

William Burkitt’s Commentary

Here our Saviour foretells his approaching death, that within a little time the men of the world should see him no more; for though he rose again, the world saw him no more after his death; for we read of no appearance of him after his resurrection to any, but to his disciples only. Indeed his resurrection to any, but to his disciples only. Indeed the hour is coming when the world shall see him again: namely, at the day of judgment, when every eye shall behold him with terror and amazement.

Observe farther, The consolation given to his disciples, Ye shall see me; and because I live, ye shall live also. Because I am raised from the grave, I will quicken your dead bodies in the grave, and ye shall live also: and as I live by my ascension into heaven, so shall you my disciples live a life of grace here, and a life of glory with myself hereafter.

Learn hence, That a believer’s spiritual life is derived from Christ, who, by his spirit, communicates a quickening virtue to all his members; Because he lives, they shall live also. See how Christ binds up their life together with his own! As if he had said, “Whilst there is vital sap in the root, you that are branches in me shall not wither and die.”

Observe lastly, A farther privilege insured to believers after Christ’s ascension, and the spirit’s mission; they should more perfectly understand the essential union betwixt Christ and his members!

At that day ye shall know that I am in my Father, &c. The knowledge which the saints now have of the mysterious and mystical union, is but dark and imperfect; but in heaven they shall understand these things clearly; then and there the essential union of Christ and his Father, and the mystical union between Christ and believers, will be more clearly understood, than we are capable to understand them in this our imperfect state.