Therefore, if I come, I will bring to remembrance his works which he doeth, prating against us with wicked words: and not content therewith, neither doth he himself receive the brethren, and them that would he forbiddeth and casteth [them] out of the church.
3 John 1:8 We therefore ought to welcome such, that we may be fellow-workers for the truth.
3 John 1:9 I wrote somewhat unto the church: but Diotrephes, who loveth to have the preeminence among them, receiveth us not.
3 John 1:10 Therefore, if I come, I will bring to remembrance his works which he doeth, prating against us with wicked words: and not content therewith, neither doth he himself receive the brethren, and them that would he forbiddeth and casteth [them] out of the church.
3 John 1:11 Beloved, imitate not that which is evil, but that which is good. He that doeth good is of God: he that doeth evil hath not seen God.
3 John 1:12 Demetrius hath the witness of all [men], and of the truth itself: yea, we also bear witness: and thou knowest that our witness is true.
The verse centers on "therefore", "come", "bring", "remembrance", "works", "doeth", "prating", and "against". It is saying that the verse draws attention to "therefore" and "come", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 9's "I wrote somewhat unto the church but..." into verse 11's "Beloved imitate not that which is evil...", so "therefore" and "come" belong inside that flow. In 3 John context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "therefore" and "come" with trust shaped by these words, not by a vague optimism outside the passage.