Passage
In that day ye shall know that I am in my Father, and ye in me, and I in you.
John 14:20 (ASV)
Nearby Context
John 14:18 I will not leave you desolate: I come unto you.
John 14:19 Yet a little while, and the world beholdeth me no more; but ye behold me: because I live, ye shall live also.
John 14:20 In that day ye shall know that I am in my Father, and ye in me, and I in you.
John 14:21 He that hath my commandments, and keepeth them, he it is that loveth me: and he that loveth me shall be loved of my Father, and I will love him, and will manifest myself unto him.
John 14:22 Judas (not Iscariot) saith unto him, Lord, what is come to pass that thou wilt manifest thyself unto us, and not unto the world?
Study Lenses
The verse centers on "shall" and "father". It is saying that the verse draws attention to "shall" and "father", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 19's "Yet a little while and the world..." into verse 21's "He that hath my commandments and keepeth...", so "shall" and "father" belong inside that flow. In John context, the local focus is the identity of Jesus, new birth, eternal life, and belief and unbelief.
A plain takeaway is to answer the verse's own emphasis on "shall" and "father" with trust shaped by these words, not by a vague optimism outside the passage.