God loves to prove to worldly man that His ways are far better than what man can come up with. Let's look at some of what man thought was foolishness that God used to save His people with. We will start with Noah, his neighbors had to think he was crazy building a boat because a flood was going to happen. It had never rained before everything was perfect weather wise. Why would God destroy something that is so perfect. Yet, when the time came God proved that Noah was right.
Time and time again the Children of Israel thought Moses was being a foolish leader only to have God prove them wrong. Not only were the plagues that happend to the Egyptians for Pharoah to let them go it was also for the Children of Israel to see that God was in control and taking care of them. However, they quickly forgot when they were trapped at the Red Sea with the Egyptian army approaching. Some of the people began to question Moses' leadership then. God proved that He was still in control of the situation then by blocking the Egyptian army with fire and parting the Red Sea so that the Children of Israel could walk across to the other side on dry land. Time and again they would question Moses' leadership and time and again God provided water, food and everything else that they needed.
The little shepherd boy, David, wanting to fight in the army along side of his brothers and being told no he had to stay home and tend the flock because he was too young. Then one day when he was taking supplies to his brothers, he saw the giant Goliath mocking Israel's army and even worse mocking his God. David couldn't understand why no one els was as outraged as he was why were they all hiding from the giant. He decided that enough was enough and went to King Saul and offered to kill the giant. Saul was glad that someone had finally decided to do something that he even offered to let David wear his armor. Finding it was hard to move in the armor David left it, took some stones from a nearby stream and set off to kill Goliath. Goliath, when he saw that the only one that dared to defend Israel was a young boy without armor and only armed with a slingshot, laughed at what he thought was a foolish attempt to kill him. Goliath was proven wrong as David needed only one stone and God to knock down the giant and kill him.
To the world the greatest act of foolishness was when Jesus died on the cross. The religious leaders mocked Him saying that He saved others but could not save Himself. They were blinded to the fact that they were the ones in need of being saved and that it was His love for everyone that kept Him on the cross. Paul is the best on God using the foolish and the foolishness of the cross in 1 Corinthians 1:18-31; " For the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God. For it is written: “I will destroy the wisdom of the wise, And bring to nothing the understanding of the prudent.” Where is the wise? Where is the scribe? Where is the disputer of this age? Has not God made foolish the wisdom of this world? For since, in the wisdom of God, the world through wisdom did not know God, it pleased God through the foolishness of the message preached to save those who believe. For Jews request a sign, and Greeks seek after wisdom; but we preach Christ crucified, to the Jews a stumbling block and to the Greeks foolishness, but to those who are called, both Jews and Greeks, Christ the power of God and the wisdom of God. Because the foolishness of God is wiser than men, and the weakness of God is stronger than men. For you see your calling, brethren, that not many wise according to the flesh, not many mighty, not many noble, are called. But God has chosen the foolish things of the world to put to shame the wise, and God has chosen the weak things of the world to put to shame the things which are mighty; and the base things of the world and the things which are despised God has chosen, and the things which are not, to bring to nothing the things that are, that no flesh should glory in His presence. But of Him you are in Christ Jesus, who became for us wisdom from God—and righteousness and sanctification and redemption— that, as it is written, “He who glories, let him glory in the LORD.”