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The world is full of examples of people who were once successful but fell from Grace because they failed to continue doing those things that earned them success. Some years ago the displacement of Ovaltine by Bournvita in Nigeria is a good example.
The children of Israel learnt the hard way that it is dangerous to take success for granted. They were in disobedience because one of them had sinned. They had assumed Ai would fall easily but they failed to check on the factors that make for success.
In the book of 1Samuel 17:8, Goliath boasted before the children of Israel. His physique and track record frightened King Saul and his men. No one dare to face him. They virtually accepted defeat without putting up a fight. When David appeared on the scene, he came to see and not to fight. The boasting of Goliath welled up in him a righteous anger and he said "...for who is this uncircumcised Philistine, that he should defy the armies of the living God?"
Before David arrived everyone based success or failure on human strength. His experience was different. He knew the limitations of man and the almightiness of God.
