Passage
Greater love hath no man than this, that a man lay down his life for his friends.
John 15:13 (ASV)
Nearby Context
John 15:11 These things have I spoken unto you, that my joy may be in you, and [that] your joy may be made full.
John 15:12 This is my commandment, that ye love one another, even as I have loved you.
John 15:13 Greater love hath no man than this, that a man lay down his life for his friends.
John 15:14 Ye are my friends, if ye do the things which I command you.
John 15:15 No longer do I call you servants; for the servant knoweth not what his lord doeth: but I have called you friends; for all things that I heard from my Father, I have made known unto you.
Study Lenses
The verse centers on "greater", "love", "hath", "than", "down", "life", and "friends". It is saying that the verse draws attention to "greater" and "love", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 12's "This is my commandment that ye love..." into verse 14's "Ye are my friends if ye do...", so "greater" and "love" 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 "greater" and "love" with trust shaped by these words, not by a vague optimism outside the passage.