DOES THE TRANSIENCE OF LIFE GIVE IT VALUE? 

Atheists may tell others that they would not be happy to live in an eternal Heaven after death. Religion says that presumes too much about what God cannot do. It says God can surely make it a treasure forever.

The atheist may then say that anyone you love here and now is loved because one day they will not exist. They are like a flower that just be honoured for its beauty simply because it will not last. It will rot. It will stink. This argument is saying that the promise of eternal life is damaging and harmful. It shows a lack of love and appreciation for those who are with you now.

It does not rule out an afterlife that lasts only a few years or whatever.  But it is enough to rule out Christianity with its promise of eternal life as a valid and healthy religion.