Passage
And every one that hath this hope [set] on him purifieth himself, even as he is pure.
And every one that hath this hope [set] on him purifieth himself, even as he is pure.
1 John 3:1 Behold what manner of love the Father hath bestowed upon us, that we should be called children of God; and [such] we are. For this cause the world knoweth us not, because it knew him not.
1 John 3:2 Beloved, now are we children of God, and it is not yet made manifest what we shall be. We know that, if he shall be manifested, we shall be like him; for we shall see him even as he is.
1 John 3:3 And every one that hath this hope [set] on him purifieth himself, even as he is pure.
1 John 3:4 Every one that doeth sin doeth also lawlessness; and sin is lawlessness.
1 John 3:5 And ye know that he was manifested to take away sins; and in him is no sin.
The verse centers on "hath", "hope", "purifieth", "himself", "even", and "pure". It is saying that the verse draws attention to "hath" and "hope", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 2's "Beloved now are we children of God..." into verse 4's "Every one that doeth sin doeth also...", so "hath" and "hope" 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 "hath" and "hope" with trust shaped by these words, not by a vague optimism outside the passage.