Because iniquity shall abound ( πληθυνθῆναι, is multiplied). The word rendered "iniquity" is ἀνομι ìα, "lawlessness," general immorality and licence. Impatience of rule and discipline, connivance at and imitation of heathen practices, reacted upon the faith of believers, undermined steadfast adherence to principle.
Then was the power of "that wicked one" ( ὁἀ ìνομος, 2 Thessalonians 2:8) exercised and seen in the lapse of the unstable. The love of many ( τῶν πολλῶν, the many, the majority) shall wax cold. "Love" ( ἀγα ìπη) here is used in its general and comprehensive sense, as having God as its chief object and man in subordination thereto.
The troubles and persecutions that shall beset believers, the spirit of worldliness and self-seeking that a timid faith encourages, will issue in loosening dependence upon God and trust in his providential care; and internal dissensions will destroy that brotherly love which ought to be characteristic of Christians.
Of this lack of energetic love the Lord speaks in his warnings to the Church of Laodicea (Revelation 3:16), "Because thou art lukewarm, and neither cold nor hot, I will spue thee out of my mouth."