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 (ASV)
Nearby Context
John 1:16 For of his fulness we all received, and grace for grace.
John 1:17 For the law was given through Moses; grace and truth came through 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 witness of John, when the Jews sent unto him from Jerusalem priests and Levites to ask him, Who art thou?
John 1:20 And he confessed, and denied not; 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 through Moses..." into verse 19's "And this is the witness 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.