Man has control over it just like Cain had control over it. God told Cain "sin is crouching at the door; and its desire is for you, but you must master it". So what did Cain do? He went and murder Abel.
This is the flaw of man. We cannot master sin. We have no "free" will because we cannot master sin.
As far as Josuah's speech, he was already speaking to the choir. Once we are saved, Christians can "choose" to go off and sin. But like Jonah, God will always bring us back even though we smell like rotten fish.
I just want to be clear about a point. Cain was told by God that he must master his sin. There is, in that comment, a statement that man can indeed master sin. The problem is that Cain had no intentions of mastering sin. This is a very subtle but important point. We sin because we want to sin-we choose to sin if you will. We will NEVER choose not to sin. This is our flawed nature. God has to change this behavior.
Well, God will always reach out to us and find us, like the 1 lamb out of 100, but just like the Prodigal Son, we can walk away and stay away. God will receive us back, but we can reject Him.