1 Samuel 6:3 And they said, if ye send away the ark of the God of Israel, send it not empty, but in any wise return him a trespass offering: then ye shall be healed, and it shall be known to you why his hand is not removed from you.
The priests and diviners of the Philistines devised a plan to test Yahweh and to appease Him by returning the ark with a trespass offering. The test was to send the ark back pulled by two milk cows, who had just given birth. The cows’ motherly instinct would be to not move, but to return to their calves. But the cows headed on a straight path for Beth-shemesh and did not turn back.
The Lord condescended to their test and caused the cows to act against nature. God sent the cows to Israel. Only God, who has power over the natural order, could cause this to happen. God did this, not to pass the Philistines’ test, but to show them His mighty power.
It is unbelief to put the Lord to the test. Jesus responds to the devil with Moses’ words, “Do not put the Lord your God to the test.” Just believe the Word. That is enough. But these were unbelievers anyway. Believers don’t test; they believe. In rare instances, God orders a test, like He did with Elijah and the prophets of Baal or in the case with doubting Thomas; but in most cases, the word of Moses and the prophets is sufficient to convince.
Our faith may be tested, as gold in a furnace to purify, but God is not to be tested. He has already proven Himself at the Cross and the Empty Tomb. The Word and the Spirit convince.