If you haven't read this post by Professor Gary Gutting here is the link Beyond 'New Atheism'. You should read it...it is really good. Professor Gutting makes cogent and interesting points.
I have a few comments to make...
First, regarding this quote from Professor Gutting's post "Most believers, however, do not come to religion through philosophical arguments. Rather, their belief arises from their personal experiences of a spiritual world of meaning and values, with God as its center." That believers don't use philosophical arguments is at the root of their problem. The foundation for what they believe and the morals that guide their lives are based on ancient storybooks, personal revelation and a bet on "a religion of hope". For an in depth examination of why believers believe take a look at this study by Michael Shermer.
On the notion that the "cultural relativism" argument applies equally to religious beliefs and atheism...the "culture" of atheists and secularists is grounded in science and reasoning. Religious culture is grounded in something else as illustrated by the 5 most common answers from Shermer's study to the question 'why do you believe?':
1. The good design/beauty/complexity of the world or universe (28.6%)
2. Experience of God in everyday life (20.6%)
3. Belief in God is comforting and gives meaning to life (10.3%)
4. The Bible says so (9.8%)
5. Just Because/faith/need to believe in something (8.2%)
Can atheists find a source for meaning, purpose and ethics? All one has to do is read The Life You Can Save by Peter Singer or Good Without God by Greg M. Epstein and you will find all the evidence you need that atheists and secularists, (and humanists) are quite capable of finding meaningful and ethical ways to live.
As for the question of whether "the divine can or should be eliminated from our moral lives" I think the millions of atheists, secularists and nonreligious skeptics living moral lives and finding meaning and purpose in this world demonstrate that we are just fine without the divine.
I highly recommend reading the post by Professor Gutting and the study by Michael Shermer.
That's all I have for now.