What goes on in a Mormon Temple is not secret, it is however sacred. The public is always invited to go through a Mormon Temple in the open house prior to it's dedication.
Were you to take such a tour you will see beautiful rooms where couples are married. Since we believe that the marriages and families can be forever it is meaningful that we seek to live lives that make us worthy to be together forever.
Also, you would have been able to see where we do baptisms by proxy for our dead ancestors. We believe that baptism is one of the earthly ordinances required of us. Since not all have a fair opportunity to accept baptism during their mortal life baptisms by proxy are the only way it can be performed.
Recently a big fuss made over someone who violated church rules by being baptized by proxy for some Jewish Holocaust victoms. This is hard to accomplish and must be done with the intent of violating church policies.
However, just as on this earth, we believe a persons choice is a prime principle. They are not members of our Church just because they are baptized by someone by proxy. In the same light, my grandmother said don't seal her in a Temple Marriage to her first husband after she died. Someone did that anyway. With God, it will be as it in all things, her choice.
I mentioned "Or Saving Her Life" in the title of this article. I am going to refer you to an article where a member of our Church, a member of The United States Senate, Wiliam H King D-Utah sought to pass legislation that would have admitted 20,000 German Jewish refugee children to the Untied States. He made a great effort and was denied.
So where should the greater furor be? Certainly not in the concept of offering someone a choice, which is what proxy works in the Mormon Temples can be.
Here is a link to that article: click here