Passage
And ye know that he was manifested to take away our sins; and in him is no sin.
And ye know that he was manifested to take away our sins; and in him is no sin.
1 John 3:3 And every man that hath this hope in him purifieth himself, even as he is pure.
1 John 3:4 Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law.
1 John 3:5 And ye know that he was manifested to take away our sins; and in him is no sin.
1 John 3:6 Whosoever abideth in him sinneth not: whosoever sinneth hath not seen him, neither known him.
1 John 3:7 Little children, let no man deceive you: he that doeth righteousness is righteous, even as he is righteous.
The verse centers on "manifested", "take", "away", and "sins". It is saying that the verse draws attention to "manifested" and "take", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 4's "Whosoever committeth sin transgresseth also the law..." into verse 6's "Whosoever abideth in him sinneth not whosoever...", so "manifested" and "take" 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 "manifested" and "take" with trust shaped by these words, not by a vague optimism outside the passage.