"For I am the least of the apostles, that am not meet to be called an apostle, because I persecuted the church of God. But by the grace of God I am what I am: and His grace which was bestowed upon me was not in vain; but I laboured more abundantly than they all: yet not I, but the grace of God was was with me. Therefore whether it were I or they, so we preach, and so ye believed." (1 Corinthians 15:9-11)
Paul first describes who he was and says that he is not worthy to be called an apostle because he persecuted the church of God. Paul then says he is who he is now (an apostle) by the grace of God. This can also be applied to us, that we are who we are today because of His grace. In order for us to understand what grace is, we needed to experience the law and guilt. Let our past be the past, so that we can live for the future, as new creatures in Christ, full of grace. Grace is power, it is Truth, it is light, and it is hated, because it does not "tickle" people's ears!