John Calvin Commentary Matthew 24:12

"And because iniquity shall be multiplied, the love of the many shall wax cold." — Matthew 24:12 (ASV)

Because iniquity will abound. Every person ought to know how far and wide this evil extends, but very few observe it. For because of the greater clarity with which the light of the gospel reveals human malice, even good and well-ordered minds grow cool and almost lose the desire to practice benevolence.

Each of them reasons to himself that the duties they perform for one person or another are wasted, because experience and daily practice show that almost all people are ungrateful, treacherous, or wicked. This is undoubtedly a serious and dangerous temptation. For what could be more unreasonable than to approve of a doctrine by which the desire to do good, and the zeal for charity, seem to be diminished?

And yet, when the gospel appears, charity, which should kindle the hearts of all people with its warmth, instead grows cool. But we must observe the source of this evil, which Christ points out: many lose courage because, due to their weakness, they are unable to resist the flood of iniquity that flows on every side.

Christ, on the other hand, requires from His followers such courage as to persist in striving against it, just as Paul also urges us not to be weary of performing deeds of kindness and beneficence (2 Thessalonians 3:13). Therefore, although the charity of many, overwhelmed by the mass of iniquities, might give way, Christ warns believers that they must overcome this obstacle, lest, overcome by bad examples, they apostatize.

And therefore He repeats the statement that no one can be saved unless he strive lawfully (2 Timothy 2:5), so as to persevere to the end.