What woe awaits those who quarrel with their Maker! Does the clay pot quarrel with its maker? Does the clay quarrel with the one who shapes it, saying, "Stop, you are doing it wrong!"?"
Isaiah 45:9 (New Living Translation)
God as the Potter is the one who chooses the tools to mold us, and those tools are usually not pleasant when we try to understand them in the flesh. Not so with the Spirit of God who sees the eternal. When a person is subjected by God to processes to detach from him/her the characteristics that do not fit in His work, it is like a potter shaping the vessel that in his/her creativity he/she designed. And in such processes some of the believers get discouraged, they even say they are angry with God for what is happening to them, being the reality that God is only detaching the pieces of clay that are not part of the masterpiece that He designed.
God is the Creator of the Universe, by His word the galaxies are sustained, He affirmed the stars, He determined the number of species that would live on earth, by His breath every being is sustained. He is not the wisest nor the mightiest because there is no one to compare Him with. He is wisdom and power. So, He knows what is best for each of His children, He knows the real shape of each of His vessels. When a believer resists becoming the person he really is in Christ, he finds himself fighting with his Maker, with the One who is molding him.
A believer should not conceive in his heart that God is doing things wrong, that the Almighty has erred in choosing the path and circumstances that a believer lives, for it is as if an earthen vessel were arguing with its maker.
On the contrary, a believer must show a willingness to be formed into the vessel that God conceived in His heart before creation. Just as moistening the clay with water makes it easier for the potter to shape his work, the believer must be exposed frequently to the power and life of God's word in order to be formed painlessly and easily by the Lord.
EN 
ES