He frequently lectured on Church/State separation issues and his participation in interfaith forums provided him with the opportunity to clarify the Humanist perspective.
In a Las Vegas Review-Journal article, Lipman stated: "My biggest concern is to counter the propaganda from people who think that people who don't believe in a supernatural deity cannot live moral, ethical lives."
Lipman said his top priority "is to change people's attitudes about Humanists".
He was a life member of Freedom From Religion Foundation and the American Humanist Association.
His daughter, Lori Lipman Brown is a former member of the Nevada State Senate, former director of the Secular Coalition for America, and was co-mentor (with Mel Lipman) of the Humanist Institute class of 2012.