Lippmann describes the "crisis of faith" that is produced by the "acid of modernity" better than anybody I've read. It's not that educated people don't want to believe in traditional religion, it's that they are no longer able to. The background assumptions of Western civilization have simply been altered too much by new forms of political organization and advances in science. This would not create a crisis if people no longer had the needs that religion has traditionally filled, like the need to believe in something that makes life meaningful and which can provide an anchor for moral codes. But those needs are still there, people feel the loss, and the question is what can fill the vacuum left by the waning credibility of traditional Christianity.
Some, like J.S. Spong ('Why Christianity Must Change or Die') suggest a kind of de-mythologized or de-natured version of Christianity; but if that worked, Unitarianism would be growing a lot faster than it is. Most who tackle the issue end up leaning to some form of Eastern wisdom religion or Spinozan pantheism; Ken Wilbur ('The Marriage of Sense and Soul') is a prime example. Unfortunately, those are all difficult, intellectualized forms of religion, suitable for the small and committed minority, not for the great mass of ordinary people living ordinary, busy lives. Those religions tend to be "all theology, all the time", but most people care nothing about theology, know even less about it, and are completely correct in the assessment that implies. The details of disputes about the nature of the Trinity don't count for much when you're trying to get your kid off drugs or to cope with a positive biopsy.
For example, Advaita Vedanta is one thing, but if you look at how Hinduism is actually practiced, the popular versions are replete with magic, multiple gods and spirits, village festivals, mythical stories and superstitions: Long on consolation and self-help, short on serious theology. That works fine for ordinary people, but probably less well for many in the scientific/literary elite, who perhaps face a Hindu crisis of faith much like Lippmann describes for Christianity. For most people, elite, esoteric forms of Hinduism will never have much appeal, any more than will the difficult road of Christian Mysticism (Meister Eckhart, St. John of the Cross, etc.) in the parallel case.
Lippman argues for an essentially Stoic/Epicurean view like found in Marcus Aurelius or Lucretius. But that again is an elite form of religion, really more a philosophy of life than a religion. As a result, those ideas have been around for a very long time without attracting very many adherents.
The problem Lippman describes is real, but it's not as widespread in the population as he portrays it. I think he overgeneralized from the intellectual crowd he was part of. In that group there was/is no doubt an acute loss of faith. But the explosive growth of Evangelical Christianity in the U.S. suggests that popular forms of Christianity continue to fill the bill for most people who seek religious support. Lippmann's argument may be one that applies primarily to Western Europeans and to certain highly secular scientific/literary circles in the U.S. I think he's right that there will be no "coming to Christ" for those people, and that larger meaning and a sustainable moral anchor will have to derive from some other source. But what?
Lippmann is very cautious in presenting his suggested solution only as a possible avenue of approach, a general direction, and not in any respect a finished answer. This is a book of enormous integrity and great seriousness; it's a giant step up in class from the current pop atheism of Dennett, Dawkins, Hitches, et al. But it simply may be that some social or personal needs cannot be met by any system built on a non-transcendent foundation. For example, without some transcendent source, all systems of moral law will be subject to constant revision and reinterpretation for reasons of expediency. There is just nothing to stop that kind of opportunistic drift, because none of it came down on stone tablets, and everybody knows it didn't. The problem of holding the moral line is difficult enough, after all, with moral precepts when they are considered to be genuinely God-given.
Even if Lippmann's answer is not good enough, he sets out the problem with great depth and skill in this superbly written book. Lippmann was a public intellectual worthy of the name. Highest recommendation.