Passage
*We* know that we have passed from death to life, because we love the brethren. He who does not love [his] brother abides in death.
*We* know that we have passed from death to life, because we love the brethren. He who does not love [his] brother abides in death.
1 John 3:12 not as Cain was of the wicked one, and slew his brother; and on account of what slew he him? because his works were wicked, and those of his brother righteous.
1 John 3:13 Do not wonder, brethren, if the world hate you.
1 John 3:14 *We* know that we have passed from death to life, because we love the brethren. He who does not love [his] brother abides in death.
1 John 3:15 Every one that hates his brother is a murderer, and ye know that no murderer has eternal life abiding in him.
1 John 3:16 Hereby we have known love, because *he* has laid down his life for us; and *we* ought for the brethren to lay down [our] lives.
The verse centers on "passed", "death", "life", "love", "brethren", "does", and "brother". It is saying that the verse draws attention to "passed" and "death", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 13's "Do not wonder brethren if the world..." into verse 15's "Every one that hates his brother is...", so "passed" and "death" belong inside that flow. In 1 John context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "passed" and "death" with trust shaped by these words, not by a vague optimism outside the passage.