John 16:33 'These things I have spoken unto you, that in me ye might have peace. In the world ye shall have tribulation: but be of good cheer; I have overcome the world.'
Jesus said we would have tribulation. He did not say that He was the one bringing the tribulation or what the tribulation would be, but He said it would come. Then He made the amazing statement that in the midst of tribulation we were to be of good cheer.
Tribulations exist because there is a battle between the kingdom of God and the kingdom of the devil. When we operate in faith, God is able to grant us such victory that we are actually better off because of the battle. It's just like when a army goes to war. If they win, they gain spoils. But if they embrace their enemy because of the spoils they were expecting to receive, they will be killed instead of blessed. First, you have to fight and win the war and then, and only then, will the spoils be available. The enemy doesn't come to be a blessing, but a blessing can be obtained from the enemy if we are victorious.
Likewise, tribulations and adversities are not blessings from God. They are attacks from the enemy intended to steal the Word of God out of our lives. No man should say that the temptation came from God, for God is not the one who tempts any man (Jas. 1:13).
If problems were what perfected us, then most Christians would have been perfected long ago and those who experienced the greatest problems would be the greatest Christians. However, that's not the way it is. God's Word is given to us to make us perfect, and thoroughly furnished unto every good work (2 Tim. 3:17). God's Word does not need to be supplemented with problems to accomplish its work.