John Chrysostom

"Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in His goodness: otherwise thou also shalt be cut off."

And he does not say, Behold thy well doing, behold thy labors, but, "Behold the goodness of God" toward man, to show that the whole comes of grace from above, and to make us tremble. For this reason for boasting should make thee to fear. Since the Lord hath been good unto thee, do thou therefore fear. For the blessings do not abide by thee unmovable if thou turnest listless, as neither do the evils with them, if they alter; "For thou also," he says, "unless thou continue in the faith, wilt be cut off."