Passage
Believe me that I am in the Father, and the Father in me: or else believe me for the very works` sake.
Believe me that I am in the Father, and the Father in me: or else believe me for the very works` sake.
John 14:9 Jesus saith unto him, Have I been so long time with you, and dost thou not know me, Philip? he that hath seen me hath seen the Father; how sayest thou, Show us the Father?
John 14:10 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.
John 14:11 Believe me that I am in the Father, and the Father in me: or else believe me for the very works` sake.
John 14:12 Verily, verily, I say unto you, he that believeth on me, the works that I do shall he do also; and greater [works] than these shall he do; because I go unto the Father.
John 14:13 And whatsoever ye shall ask in my name, that will I do, that the Father may be glorified in the Son.
The verse centers on "believe", "father", "else", "very", "works", and "sake". It is saying that the verse draws attention to "believe" and "father", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 10's "Believest thou not that I am in..." into verse 12's "Verily verily I say unto you he...", so "believe" 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 "believe" and "father" with trust shaped by these words, not by a vague optimism outside the passage.