Are Quakers Christian?

Steven Davi­son takes on one of the trick­i­er ques­tions of mod­ern lib­er­al Quakerism:

I am going to make a bold apol­o­gy for a clar­i­fied lib­er­al Quak­er iden­ti­ty that retains its roots and recov­ers wor­ship in the spir­it of Christ, but yet releas­es us from the ortho­dox Chris­t­ian pre­oc­cu­pa­tions that no longer speak to so many unpro­grammed Friends. 

Are Quak­ers Christian?