@schopenhauer1 ... the Shortcomings of Popular Secularist Philosophies, or secularism in general?
Harvey Cox, a distinguished and maybe even popular theologian (he's 95 years old) wrote The Secular City in 1964. This was at a time when the people in the pews had noticed the EXIT signs over the church doors and were leaving the church, mostly to not return, Secular institutions--government, media, entertainment, corporations, education, etc. were becoming more dominant in society, not just in the US, but around the world.
Cox proclaimed that God was as present in secular societies as in any religious one, because God is present at all times and in all places, whether we like it or not. The problem of believers, per Cox, is to discern God, and discern what it means to believe in God, and be Christian in the middle of societies organizing or reorganizing around secular principles.
There is nothing to be done about secularism. It has developed over time and been driven by various processes, like industrialism, technology, and so on. It is a fact of life; it's the world we live in; it isn't going away; it isn't the enemy.
The Secular City made a very big impression on my 17 year old brain in 1964, and it's had an enduring influence. I was brought up in a religious (Protestant) home, and Christianity, whether I like it or not, is the core of my 'operating system'. There were / are conflicts between core beliefs and current realities. When the choice was between physically affirming my gayness and faith, the Christian condemnation of homosexuality--and promiscuous, anonymous, hedonistic sex in general, gay or straight--had to be dumped over-board. Sexuality was the right choice and the church was wrong. (And, of course, more power to those who love monogamously till death do them part.)
Still, God is present in the gay bath house, the brothel, and walks with the street whores (aka sex workers). If God worries about sparrows, God also worries about the well-being of "degenerate" members of the community. The preaching of Jesus is relevant in all places, (brothel or corporate board room) something most of us find quite inconvenient.
Secularism may be accommodating to the least among us, but just as likely, it may be dismissive or punitive--like the neglect of the homeless living on the street. That certainly describes the church's overall approach--cue the pogrom, the stake and firewood, public humiliations, etc. Jesus still stands against all that, even if it is all done in His name.
God, Jesus, and salvation are motivations one won't find in secularism. There are other motivations, of course, and I'm not knocking them.
I've been far more secular than religious for decades. If I am standing up religion here, it is just to say that IF a secularized individual needs some rock solid moral directives, religion does offer them. Just don't get carried away and turn them into cruelty, bigotry and oppression (like stoning apostates to death or burning heretics at the stake).