I don't write the above as an attack on Paul. Paul makes no efforts at denying his past. [See 1st Timothy 1:15-16 and Acts 9:1-2]
Rather, I remind people of this because it seems to me Christians are particularly guilty of all manner of sin in how we consider and deal with those of storied past.
There are many tracts of Conservative Christians whose sense of moral superiority is nowhere more clearly shown than when they describe their opinions of those with unsavory brushes in their history.
More liberal Christians, while being in general less disposed to such contempt, are somewhat compromised for a different reason. Those with a history bespeckled by violence, especially violence toward the innocent, the weak, children, or women, are likely the ones in most need of help as they work to make a life in a world where all roads lead uphill. Unfortunately, those in the more liberal regions of Christianity, who might normally be the most willing to help those in need, can find themselves having a bit of cardiac dissonance when trying to bless those whose previous activities have run so counter to their general principles of peace and pacifism and so tragically victimized the groups they are most sympathetic toward.
There's a great deal of heated discussion and opinion regarding how the Christian church should view certain groups, in particular homosexuals and women. The former is traditionally censured, the latter restricted. The reason behind these battles is largely the basic meme of "it's not their fault?" [Which sorta sounds stupid when referring to women, but I think people understand what I mean.]
The idea is that someone should not be restricted or censured based on whatever qualities they are born with, whether that be race, orientation, or gender. And it is this meme pitted against a view that arguably rejects it that causes the tension in the church and society.
But none of that is true regarding the group "people with an unsavory past." There is no real battle being waged regarding how they should be treated. No respectable Christian church can openly denounce or cast negativity toward such individuals without being in severe contradiction of Christ's own teachings, yet you also do not see much in the way of people advocating more awareness in the church or exhorting people to actively help these people. It is a hypocritical luke-warmedness that comes from a minority suffering no institutionalized discrimination nor having a champion to attack the more subtle, unofficial variety of the same.
You don't see anyone standing up for compassion and forgiveness in this arena because there's no particular doctrine or statute to attack, only people's dispositions, which generally cannot be bothered with anything as silly as appeals to scripture or logic.