Below is an excerpt from A.W. Tozer's book, The Root of the Righteous. Enjoy!
The test by which all conduct must be judged is motive.
As water cannot rise higher than its source, so the moral quality in an act can never be higher than the motive that inspires it. For this reason no act that arises from an evil motive can be good, even though some good may appear to come out of it. Every deed done out of anger or spite, for instance, will be found at last to have been done for the enemy and against the Kingdom of God.
Unfortunately the nature of religious activity is such that much of it can be carried on for reasons that are not good, such as anger, jealousy, ambition, vanity and avarice. All such activity is essentially evil and will be counted as such at the judgment.
In this matter of motive, as in so many other things, the Pharisees afford us clear examples. They remain the world’s most dismal religious failures, not because of doctrinal error nor because they were careless or lukewarm, nor because they were outwardly persons of dissolute life. Their whole trouble lay in the quality of their religious motives. They prayed, but they prayed ot be heard of men, and thus their motive ruined their prayers and rendered them not only useless but actually evil. They gave generously to the service of the temple, but they sometimes did it to escape their duty toward their parents, and this was evil. They judged sin and stood against it when they found it in others, but this they did from self-righteousness and hardness of heart. So with almost everything they did. Their activities had about them an outward appearance of holiness, and those same activities if carried on out of pure motives would have been good and praiseworthy. The whole weakness of the Pharisees lay in the quality of their motives.
That this is not a small matter may be gathered from the fact that those orthodox and proper religionists went on in their blindness till they at last crucified the Lord of glory with no inkling of the gravity of their crime.
Religious acts done out of low motives are twice evil, evil in themselves and evil because they are done in the name of God. This is equivalent to sinning in the name of the sinless One, lying in the name of the One who cannot lie and hating in the name of the One whose nature is love.
Christians, and especially very active ones, should take time out frequently to search their souls to be sure of their motives. Many a solo is sung to show off; many a sermon I preached as an exhibition of talent; many a church is founded as a slap at some other church. Even missionary activity may become competitive, and soul winning may degenerate into a sort of brush-salesman project to satisfy the flesh. Do not forget, the Pharisees were great missionaries and would compass the sea and land to make a convert.
A good way to avoid the snare of empty religious activity is to appear before God every once in a while with our Bibles open to the thirteenth chapter of First Corinthians. This passage, though rated one of the most beautiful in the Bible, is also one of the severest to be found in Sacred Writ. The apostle takes the highest religious service and consigns it to futility unless it is motivated by love. Lacking love, prophets, teachers, orators, philanthropists and martyrs are sent away without reward.
To sum it up, we may say simply that in the sight of God we are judged not so much by what we do as by our reasons for doing it. Not what but why will be the important question when we Christians appear at the judgment seat to give account of the deeds done in the body.