Woe to the one who quarrels with His Maker— A piece of pottery among the other earthenware pottery pieces! Will the clay say to the potter, ‘What are you doing?’ Or the thing you are making say, ‘He has no hands’?
Isaiah 45:9 (NASB)
We often think that we know better than God what He should do in a given situation. This is what sometimes leads us to question Him or to doubt His sovereignty. When faced with a situation, instead of trying to figure out why God is letting us go through this ordeal, we prefer to challenge Him or turn away from Him to find the answer elsewhere.
In this verse, we see God speaking to the prophet Isaiah saying, “Woe to him who contends with Him". Here, "Contend" means questioning God's decisions and actions in our lives. God is the creator. If you're still alive and well, it's because He cares about you. So when things go wrong instead of questionning Him, it's better to humble yourself and ask Him to reveal to you what He wants to teach you.
As the verse says, you are but clay in the hands of God. It is He who decides the form He wants to give you. As much as He is not satisfied, He will start over again. The form is your attitude, your lifestyle, your faith in Him, your obedience to His word and your good works. To mold you, He will use trials and circumstances as much as possible. God knows where He's taking you, so don't challenge His decisions because you'll lose every time.