Please read the excellent book Who Is My Brother?: Facing a Crisis of Identity and Fellowship, by F. LaGard Smith (Nashville: Cotswold Publishers, 1997), ISBN 0-9660060-0-3.
Smith discusses how we should relate to (1) all people, (2) those who believe in Christ, (3) those who have been immersed, (4) those who have been immersed for forgiveness of sins, and (5) Restoration Movement members with whom we may not see eye to eye.
A must-read.