Joel 2:2
A day of darkness and of gloominess, a day of clouds and of thick darkness, as the morning spread upon the mountains: a great people and a strong; there hath not been ever the like, neither shall be any more after it, even to the years of many generations.
The verse points to a coming day of clouds and thick darkness that is near, a terrible crisis fast approaching. That time arrives as the Spirit of God is being withdrawn from the earth. It is a time when drunkenness, insanity, revelry, and crime are rapidly increasing and many lives will go out in darkness.
The warning is to study God's word now and learn its plain truths. This preparation is so one can give a reason for hope and stand firm in conflict, instead of wishing too late that one had done so. The response called for is to press together in unity and to cease criticism of one another. It requires showing Christ's tenderness toward brethren, bowing before God in true humility of soul, and giving oneself to proclaiming the truth for this time.