Christianity is a religion of new beginnings.  Jesus died for our sins, so that we may have new life.  A life that is not tainted by our past.  It’s not that our past doesn’t matter.  Our past must be confronted and dealt with but Catholics are given that all important sacrament of reconciliation.  As long as we deal forthrightly with our past we are not doomed by it.  Our life can have a new beginning.  Our future is not determined by our past.  He did not ask the fisherman if they were righteous, he asked them to drop their nets and follow him.  That is all Jesus ever asks of us, to follow him.