Passage
No man hath seen God at any time: the only begotten Son who is in the Bosom of the Father, he hath declared him.
John 1:18 (DRB)
Nearby Context
John 1:16 And of his fulness we all have received: and grace for grace.
John 1:17 For the law was given by Moses: grace and truth came by Jesus Christ.
John 1:18 No man hath seen God at any time: the only begotten Son who is in the Bosom of the Father, he hath declared him.
John 1:19 And this is the testimony of John, when the Jews sent from Jerusalem priests and Levites to him, to ask him: Who art thou?
John 1:20 And he confessed and did not deny: and he confessed: I am not the Christ.
Study Lenses
The verse centers on "only begotten Son", "hath", "seen", "time", "bosom", and "father". It is saying that the verse draws attention to "only begotten Son" and "hath", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 17's "For the law was given by Moses..." into verse 19's "And this is the testimony of John...", so "only begotten Son" and "hath" 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 "only begotten Son" and "hath" with trust shaped by these words, not by a vague optimism outside the passage.