A human being who replicates such an existence is on the level of an animal. It is not an all or nothing propostion. To the extent that we live lives imbued with spirituality and purpose we become that much more human. The less spiritual - the more animalistic. It is frightening to consider that humans can be animals but so is the reality. I claim that they are WORSE than animals for animal have no seichel and cannot do any better. But a human being who doesn't use his capacity to choose a life of spirituality and lives a completely material existence is much worse.
Rav Kook, that great lover of man, has a passage where he talks about atheists and agnostics. He says that they are basically two legged animals....
But he says yet more.... Let's see for ourselves:
הכופר שאין לו קישור בענין אלהי, אין לו באמת צורת אדם, ואין מגמת-חייו חיים של אדם כלל. כל הרגשותיו הנם רק בהמיות, ואפילו אם יהיה איש מלא דעה וחכמה, ומלא מוסר ויושר כפי הנראה, אין זה כ"א כמו בהמה מלומדת ובעלת תרבות, אבל רוח האדם בכל עומק הוייתו, אינינו נופח כי אם עם הקישור אל הענין האלהי העליון
The Rv adds that even if he has a Phd, reads academic journals, and he seems to be a really decent upright person - he is merely like a tamed, well trained animal. [Exhibit A: The Nazis before the war. Dignified, educated and refined. During the war - untamed beasts ימ"ש.] But an animal he remains for he lacks the spirit of man in all of the depths of its being. This spirit only inheres in a person who is connected to Hashem.
[Shmoneh Kvatzim 1/ 327 - see the rest of the passage where he is מלמד זכות on the kofrim of his generation. I don't share his optimism about the kofrim of ours....]
