The prophet Jeremiah writes, “The heart is more deceitful than all else and is desperately sick; who can understand it?” (17:9). Some of you may be acquainted with the popular Christian writer, John Eldridge. One of his beliefs is that the hearts of Christians are good and can be trusted. I think I know what he means but it is not the whole truth. Yes, believers in Christ have been given the gift of the Holy Spirit and are the subjects of His cleansing and renewing work within, but we are most of us a work in progress. We do have good desires which are from God but we also have bad desires within us. John Eldridge may deny that these bad desires belong to the “heart” of a Christian believer but that is only be restricting the definition of heart.

Jesus says, “For from within, out of the heart of men, proceed evil thoughts, fornication's  thefts, murders, adulteries, deeds of coveting and wickedness, as well as deceit, sensuality, envy, slander, pride and foolishness.” (Mark 7:21-22) Now, if Jesus says these things flow out of the heart of men and most Christians will acknowledge that they have experienced at least some of these evils within themselves then we must heed the caution that Jeremiah gives us above. In Proverbs we read, “Watch over your heart with all diligence, for from it flow the springs of life.” If the heart was entirely safe he would not tell us to watch over it! It can fool us if we are not careful and it will unless we rely upon God’s Spirit.

The obvious problem is when the heart tricks us into believing good is evil and evil good or when it seeks to justify disobedience to God. But there is another way it tricks us and it is one of the worst because it makes us think we are seeking God and eternal goods when we are really seeking mere worldly goods for self-gratification. We appear to ourselves and to others (though not always to them) as though we are great lovers of God and of His kingdom. We pray, we worship, we give of our time and treasure to God’s work, we serve the poor and needy and seek to lead others to Christ, yet we are unaware of how much we do this for reasons that are essentially selfish and worldly.

But God knows our heart. Jeremiah 17:10 says, “I, the Lord, search the heart; I test the mind, even to give to each man according to his ways, according to the results of his deeds.” The results of selfish, worldly intentions are, in the long run, disastrous and destructive. If we will allow God to search our hearts in this life, to uncover the deceits of our hearts and set us free from them, we will be most blessed and happy. We may avoid looking into the mirror all our lives but there is a day, appointed by God, when all men will be made to look and then we will see what we have been avoiding all our lives and then it will be too late to change.

Jesus warned His disciples against behaving as the Pharisees who practiced their righteousness in order to be seen and praised by men. They have their reward already, said Jesus. (Matthew 6:1) I am sure that the Pharisees were convinced in their own minds that they were seeking God’s approval and not men’s but that they had allowed themselves to be fooled by their own hearts. They were not following the Spirit of God but merely the letter of the law and so were easy prey to their deceitful hearts. And so may we be fooled if we do not pay attention to the inward revelations of God’s Spirit. It is like walking past a mirror and suddenly catching sight of what you really look like. You thought you looked quite presentable but you discover that there are stains on your clothes and your hair is a mess! You could just avoid looking at mirrors, of course, and that is just what many of us do, spiritually. We do not look into the mirror of God’s word in the light of His Holy Spirit.

The Spirit of God will show us when we are not really seeking first God’s kingdom and righteousness but our own worldly lusts and pride. But He will also heal our desperately sick hearts by giving us a fresh glimpse of our glorious Lord, Jesus Christ. Our hearts are purified by faith (Acts 15:9). “But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory…” (2 Corinthians 3:18) We see not only ourselves, poor, blind and wretched, but our wonderful Lord and in that glimpse of Him, we are healed. We suddenly see how all the low and selfish things we were aiming at are as nothing compared with Him and His love.

Before, we prayed and worshiped and served in order to be seen and approved of men or because it fulfilled a social or psychological need. But now that we have seen what our motives actually were and have caught a sight of the One for whom all things should be done and for whose blessing and approval all work should be performed, we serve with a truly humble and joyful spirit. We no longer feel wretched when people fail to notice our righteous deeds or pious practices. Our eyes are upon God and pleasing Him because He has so loved us. This is what it means to have a pure heart and, as Jesus promised, “The pure in heart shall see God.” (Matthew 5:8)