Paul Shown Mercy Because He Had Good Excuse?

In today's reading Paul says in 1 Timothy 1:13, "Even though I was once a blasphemer and a persecutor and a violent man, I was shown mercy because I acted in ignorance and unbelief." It almost sounds like Paul is saying, "God had mercy on me because I had a good excuse; I didn't know any better." But that is not what Paul is saying. Before any of us come to faith we live in ignorance and unbelief like Paul. It's only through God's mercy that we come to believe in him. What prevents belief and reject God's mercy is an intentional hardening of the heart against God, which Paul had not done.