A Christian must keep a watch and guard against envy and malice, or any bitterness of spirit
These things are the very reverse of that great and distinguishing thing in Christianity—the very essence of Christianity.
It behooves Christians, as they would not by their practice directly contradict their profession of Christianity, to take heed to themselves as to this matter. They should suppress the first beginnings of ill-will, and bitterness and envy, watch strictly against all occasions of such a spirit, strive and fight to the utmost against such a temper as tends that way, and avoid as much as possible all temptations that may lead to it.
A Christian should at all times keep a strong guard against everything that tends to overthrow, or corrupt, or undermine a spirit of love.
That which hinders love to men will hinder the exercise of love to God; for, as was observed before, the principle of a truly Christian love is one. If love is the sum of Christianity, surely those things which overthrow love are exceedingly unbecoming Christians.
An envious Christian, a malicious Christian, a cold and hard-hearted Christian is the greatest absurdity and contradiction. It is as if one should speak of dark brightness, or a false truth!
Adapted from Ethical Writings, The Works of Jonathan Edwards (Yale University Press, 1989), 146–147.