Commentaries:
Robertson's Word Pictures (NT)
And he is longsuffering (makroqumei). This present active indicative comes in awkwardly after the aorist subjunctive poihsh after ou mh, but this part of the question is positive. Probably kai here means "and yet" as so often (John 9:30; John 16:32, etc.). God delays taking vengeance on behalf of his people, not through indifference, but through patient forbearance.
Other Robertson's Word Pictures (NT) entries containing Luke 18:7:
Acts 7:24
2 Corinthians 7:11
Hebrews 10:30
James 5:7
1 Peter 2:14
Revelation 6:10
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