Then how is Abraham an example to us? Paul tells us that he serves as the paradigm case of the earth-shattering truth that God justifies (declares righteous) those who are in themselves “wicked” – not on the basis of works, but through faith in the promise. If Abraham could not be justified by his own righteousness, how can the rest of us who claim Abraham as our forefather? Abraham is an example to us of the fact that God justifies the wicked.
Horton, Michael; The Gospel Driven Life: Being Good News People in a Bad News World; Baker Books; Grand Rapids, MI; Copyright 2009; page 138-139