Matthew 24:12 - Albert Barnes' Notes on the Bible

And because iniquity ... - The word “iniquity” here seems to include the cruelty of the Jews and Romans in their persecutions; the betraying of Christians by those who professed to be such; and the pernicious errors of false prophets arid others. The effect of all this would be, that the ardor of feeling of many Christians would be lessened. The word “wax” means to “become.” It is an old Saxon word, not used now in this sense except in the Bible. The fear of death, and the deluding influence of false teachers, would lessen the zeal of many timid and weak professors; perhaps, also, of many real but feeble Christians.