Is Your Conscience Your Guide?

I have been studying through the book of Acts.  I have twice noticed that Paul stated that his conscience is clear in 23:1 and 24:16 as he stands before the Sanhedrin and Governor Felix.  What is the purpose of our conscience?  Paul knew his conscience was clear because he was following completely the calling of the Lord Jesus Christ and he was completely free of guilt before man.  This is important because he was being accused of things that violated his status as a law keeping Jew.  Conscience was a matter of obedience.  I find my conscience is tied very tightly to my obedience.  My obedience likewise is tied to my commitment to live Christ through me.  I could never have a clear conscience through my own efforts.  It is only when I live from the overflow of Christ in my life that I have a clear conscience.  Romans 3:15 says our conscience alternately either “accuses us or defends us”.  What is the difference – on what we stand.  Do we stand on the rock of the gospel or do we stand on our own merits?