Only someone who has belief in an afterlife can dismiss the friendships of another so completely. A person who shares so much in common with another should be a friend for life.
With belief in an afterlife another chance always awaits for reconciliation with another, so this life becomes unimportant, and friendships that could be had are wasted.
Despite the overwhelming evidence that this is it, many deep within their psyches still hold to the idea that this can not be the only life. After all, our remarkable sentience makes this unacceptable.
Nevertheless, this is the case. A person who claims to not believe, really does. This life becomes unimportant. Only the hope of the next life remains. Suicide bombers become possible. Trashing a friendship also becomes possible.