Having attended seminary with many Salvation Army adherents at Asbury Seminary, a methodistic seminary in central Kentucky near Lexington, I can authoritatively state that the Salvation Army, in terms of their religion, is a separate, evangelical, methodistic denomination. It is a matter of history that the Salvation Army is out of the traditional methodist movement.
However one might desire to understand this is of no significance. We might like to view the SA as a charitable organization. It is but it isn't solely that. We might like to view it as one of many local, social service agencies. It performs in that capacity, but only because of proximate interests.
The SA is a conservative, evangelical, protestant Christian movement.
If a conservative, evangelical protestant Christian wants to know if you are a "Christian," he is actually trying to be pretty broad-minded. He doesn't want to hear that you are episcopalian, presbyterian, assemblies of God, OR....CATHOLIC.
He wants to hear: "Yes, I believe in Jesus Christ."
Others can kick at that all they want, but in doing so, they simply highlight their inadequate understanding of conservative, evangelical Christian denominations.
If the priest asks me, "Are you Catholic?" he doesn't accept Episcopal as an answer.
It would be similar to a priest hiring a secretary for the parish and asking if she was a Catholic and the interviewee responded by saying: "I'm a Christian". Would anyone be surprised if she were turned down for the job?
The simple fact of the matter is that Mr. Clark is suing the Salvation Army because they didn't like his parochial response to a broad non-denominational question. He failed the interview and is now blaming the interviewer. In light of his litigious attitude, I would have to question whether or not he would have been telling the truth if he had said yes.