1 Timothy 1v15-16
The saying is trustworthy and deserving of full acceptance, that Christ Jesus came into the world to save sinners, of whom I am the foremost. But I received mercy for this reason, that in me, as the foremost, Jesus Christ might display his perfect patience as an example to those who were to believe in him for eternal life.

We are never too far gone for Christ to make us whole, to make us an example of His glory to those around us. Paul persecuted Christianity to the point of murder yet God used Him in spite of all that to shape believers for over 1900 years and counting. No matter what we have struggled with Christ can redeem. God loves using the down and out to prove the point of His power and goodness.