God will not show grace forever. "Behold, now is the accepted time; behold, now is the day of salvation." 2 Cor. 6:2. Every "day" must close at last, and every "time" must end. The "accepted time" has lasted almost twenty centuries; the "day of salvation" has been lengthened out more than nineteen hundred years.
But another "day" is coming. The sun of salvation's day will suddenly set at the coming of the Lord, and with His advent will be ushered in the awful "day of the vengeance of our God." Isa. 61:2.
"Today if ye will hear His voice, harden not your hearts." Heb. 3:7, 8.