For God so loved the world, that he gave his only begotten Son, that whosoever believeth on him should not perish, but have eternal life. For God sent not the Son into the world to judge the world; but that the world should be saved through him.
John 3:14 And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up;
John 3:15 that whosoever believeth may in him have eternal life.
John 3:16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth on him should not perish, but have eternal life.
John 3:17 For God sent not the Son into the world to judge the world; but that the world should be saved through him.
John 3:18 He that believeth on him is not judged: he that believeth not hath been judged already, because he hath not believed on the name of the only begotten Son of God.
John 3:19 And this is the judgment, that the light is come into the world, and men loved the darkness rather than the light; for their works were evil.
The verse centers on "world", "only begotten Son", "believeth", "saved", "loved", "gave", "whosoever", and "should". It is saying that the verse draws attention to "world" and "only begotten Son", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 15's "that whosoever believeth may in him have..." into verse 18's "He that believeth on him is not...", so "world" and "only begotten Son" belong inside that flow. In Jesus Explains God's Saving Love, the local focus is new birth, eternal life, belief and unbelief, and God's saving love.
A plain takeaway is to answer the verse's own emphasis on "world" and "only begotten Son" with trust shaped by these words, not by a vague optimism outside the passage.