Well, sirs! remember what became of those who excused themselves out of heaven, by their carnal apologies, and secular businesses: Luke 14:16-24.

“But they all alike began to make excuses. The first said, ‘I have just bought a field, and I must go and see it. Please excuse me.’ Another said, ‘I have just bought five yoke of oxen, and I’m on my way to try them out. Please excuse me.’ Still another said, ‘I just got married, so I can’t come.”

The true reason why they would not come to the supper that the King of kings had invited them to, was not because they had bought farms and oxen—but because their farms and oxen had bought them. The things of the world and their carnal relations had taken up so much room in their hearts and affections, that they had no stomach to heaven’s dainties; and therefore it is observable what Christ adds at the end of the parable, “If anyone comes to me and does not hate his father and mother, his wife and children, his brothers and sisters—yes, even his own life—he cannot be my disciple. And anyone who does not carry his cross and follow me cannot be my disciple.” Luke 14:26,27.

By these words, it is evident, that it was not simply the farm nor the oxen, nor the wife—but a foolish, inordinate, carnal love and esteem of these things, above better and greater blessings, that made them refuse the gracious invitation of Christ.

They refused the grace and mercy of God offering in the gospel, under a pretense of worldly business; and God peremptorily concludes, that not a man of them should taste of his supper. And indeed what can be more just and righteous, than that they should never so much as taste of spiritual and eternal blessings, who prefer their earthly business before heaven’s dainties; who, with the Reubenites, prefer a country commodious for the feeding of their cattle, before an interest in the land of promise.

Thomas Brooks, The Secret Key to Heaven: The Vital Importance of Private Prayer

The essence of idolatry is the entertainment of thoughts about God that are unworthy of Him. It begins in the mind and may be present where no overt act of worship has taken place.

”When they knew God,” wrote Paul, “they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.”

Then followed the worship of idols fashioned after the likeness of men and birds and beasts and creeping things. But this series of degrading acts began in the mind. Wrong ideas about God are not only the fountain from which the polluted waters of idolatry flow; they are themselves idolatrous. The idolater simply imagines things about God and acts as if they were true.

Perverted notions about God soon rot the religion in which they appear. The long career of Israel demonstrates this clearly enough, and the history of the Church confirms it. So necessary to the Church is a lofty concept of God that when that concept in any measure declines, the Church with her worship and her moral standards declines along with it. The first step down for any church is taken when it surrenders its high opinion of God.

Before the Christian Church goes into eclipse anywhere there must first be a corrupting of her simple basic theology. She simply gets a wrong answer to the question, “What is God like?” and goes on from there. Though she may continue to cling to a sound nominal creed, her practical working creed has become false. The masses of her adherents come to believe that God is different from what He actually is; and that is heresy of the most insidious and deadly kind.

The heaviest obligation lying upon the Christian Church today is to purify and elevate her concept of God until it is once more worthy of Him – and of her. In all her prayers and labors this should have first place. We do the greatest service to the next generation of Christians by passing on to them undimmed and undiminished that noble concept of God which we received from our Hebrew and Christian fathers of generations past.

- A. W. Tozer, The Knowledge of the Holy (emphasis added)

ht: John Piper