The Definition of Christian is : relating to or professing Christianity or its teachings (and that is from the  most liberal dictionary on the web - Google).
If the marriage you attended celebrating two women's love for another was claiming to be a "Christian Church", they are lying. Jesus taught clearly in several places about God's intention for family and marriage for that matter. I am sure you were touched and excited to see this, but neither the Church, nor the ceremony itself can be sanctioned as "Christian".  I believe homosexual marriage is wrong, but under the laws of the land they are entitled to marry, but that does not make it right in the view of the Bible or God. If holding a Biblical view of marriage intimidates or angers you, that is your right.