I believe that adoption promotes spiritual values in society. One of the values is promotes is love. Often kids that are put up for adoption come from abusive or neglectful homes and have no clue what it means to be loved and valued. A loving family that can adopt such a child can show the child that love can exist.
For a society, it shows love and care for children and their well-being. It can also provide a sense of hope for other generations that future children will have homes to live in and good people to live around. I do believe ones spiritual values are highly influenced by the people around them, whether it be loved ones, friends, or even media.