You are right to think about Reb and Pastor Henry as a good duo to compare and contrast. In fact, in the book Have a Little Faith written by Mitch Albom, Reb and Pastor Henry are both religious teachers or leaders. (This is the first comparison.) The book is based on conversations the author had with each of these leaders. Albom wrote the book because Rabbi Albert Lewis, Reb, asked him to write the eulogy for his funeral. Albom agreed, with the stipulation that these discussions for the book were to take place.
Reb (which is short for the Yiddish word for Rabbi) is from an affluent community in New Jersey. He is eighty-two and on his death bed. Through asking the questions to construct the eulogy, they create a truly beautiful relationship that grows into a deep friendship full of faith and love and trust. Reb is always truthful, even if the answers hurt. Albom realizes that these conversations are more of a gift than his eulogy could ever be for the Rabbi.
On the other hand, Pastor Henry is an African American protestant minister from a low socio-economic neighborhood in Detroit. Pastor Henry is an African American minister in a Church so poor that the roof leaks. It is an urban church serving a largely homeless population. An outcome of the conversations with Pastor Henry was the creation of the A Hole in The Roof Foundation. This is a non-denominational foundation which helps faith groups who work with the homeless population take care of the properties which these groups utilize. Albom learns much about how, even in the midst of poverty, one holy man can make a difference.
In conclusion, Albom has been taught something very important from two very different religious men: one Jewish and one Christian. In the process, Albom found how much faith is truly divisive around the world. From conversations and mini-stories or sermons delivered by Reb, Albom begins to focus more deeply on his own faith and what it means in the greater sense of faith in the world. So, in reality, it is Albom who explores his own self in the midst of exploring these two characters.