Philippians 3 was written by a convert, the Apostle Paul, to other converts and thus raises the important question of its meaning and relevance for those of us who are not converts. Converts, if they convert for religious reasons, tend to be zealous and committed to their new faith. In the Christian tradition, particularly among Protestants, converts tend to view their past negatively—it was evil—and their conversion as turning from evil to the good. Thus, in Philippians 3 Paul counted as loss his own past as a Pharisee who kept the Law perfectly. For Jesus sake, he wrote, "I have suffered the loss of all things, and I regard them as rubbish, in order that I may gain Christ." (3:8 NRSV) In that same vein, he wrote that he had forgotten everything that was behind him and was "straining forward to what lies ahead." (3:13) Although he acknowledges his own shortcomings, Paul still advised his readers, as one convert writing other still newer converts, to follow his example (3:17); and he shows clear disdain for those who do not display the same level of commitment, zeal, and single mindedness to the cause they he feels.
For some converts, Christian faith is a matter of stepping across a sharply drawn boundary between past and present. It was certainly that for Paul. This Pauline and early church model for conversion, again especially among Protestants, has been taken to be the norm by which "real faith" is measured. As such, however, it is a mixed blessing at best. On the upside, the dedication and enthusiasm converts bring to their new faith contributes to the renewal of the faith. On the downside, that dedication and enthusiasm can too easily morph into a narrow-minded zeal. It also obscures the basic developmental reality of the life of faith, which is that it is a process of growth in maturity. It is not a one step crossing of a line even for those who take such a step. It is a life-long process.
The point here is that we have to read Philippians 3 with a grain of salt esp. when it comes to putting the past behind us. In fact, our living accumulation of experiences is always the foundation on which we build the future. If putting the past behind us means learning better ways of being faithful, then we do need to keep moving ahead on the path of faith. If, however, it means discarding the past and ignoring it then we are only fooling ourselves about what it means to grow in faith and more likely to repeat past behaviors only cloaking them with the label "Christian". Paul, in sum, is a model for the Christian faith and not the model. One size does not fit all—not even his.