Christianity views the New Testament as superseding the Old.
Followers of Jesus of Nazareth and his message of love and forgiveness and universal fellowship consider those teachings to override anything to the contrary in the Old.
In truth, for Christians following the core teachings of Jesus of Nazareth, the Old Testament merely serves as backup for anything not updated and covered in the New.
This is not really accurate, the New Testament does not supersede the Old, without the Old we would not know who Jesus is. The Old is what leads us to Jesus the savior.
But it was correctly stated by someone in this thread that many of the rules and regulations of the Old Testament were given to a specific group of people at a specific time. That is why they are not followed today, not because they have been superseded, but because
they were never meant for us.
And, when you get right down to it...
Mainstream Christianity teaches that one must hate (shun) the Sin, but love the Sinner.
Yes, mainstream Christianity does teach that, too bad it is not found in the bible.