This is a difficult verse, but it is bound to be significant, for it contains the first reference in the Bible to God’s judgment. The word for “strive” is almost always elsewhere rendered “judge,” or “judgment.” It is used in Deuteronomy 32:36 (“the LORD shall judge his people”). Thus our text seems to be telling us that, before the Flood, the Holy Spirit was directly dealing with people in judgment because of their increasing involvement with sin and rebellion against the Lord. God, through the Holy Spirit, was working earnestly in the antediluvians to enable them, before His written Word was available, to discern right and wrong, but their insistent rebellion would soon lead to such depravity that God would leave them altogether, and send the destroying, cleansing Flood.
In this more enlightened age, with the complete Bible available and the saving work of God’s Son now well known, the Holy Spirit has a new judging ministry: “When he is come,” Jesus said, “he will reprove the world of sin, and of righteousness, and of judgment: Of sin, because they believe not on me; Of righteousness, because I go to my Father, and ye see me no more; Of judgment, because the prince of this world is judged” (John 16:8-11).
This time man has been given not 120 years, but almost 2,000 years to respond to the convicting judgments of the Holy Spirit, yet “evil men and seducers . . . wax worse and worse” (2 Timothy 3:13). Thus judgment is imminent once again, and to those who have “done despite unto the Spirit of grace” (Hebrews 10:29), the next time will not be merely a cleansing flood. “For our God is a consuming fire” (Hebrews 12:29). HMM http://www.icr.org/article/6101/