Regarding 'Oneness Pentecostals'?

Do you believe that a person who has not been baptized by total immersion in water cannot be truly saved? I seem to get the impression that many do believe this and I wonder what your thoughts are regarding people like The Salvation Army who do not baptize. There are other denominations also who do not baptize by immersion so do you believe that they are 'lost' - even those who have a wonderful testimony to give and will praise the Lord through their life, work and words?