Where Secular Humanism comes into difficulties is with ethics. Atheitsts who like science fall across the political spectrum. How can one position say that they alone represent the interests of humanity while the other positions, all deeply felt, do not? Some philosophies associated with atheism, such as contemporary communism on the one side, and the untrammeled capitalism of Ayn Rand on the other, are downright pernicious. I haven't met a lot of communists among my mathematical colleagues, but unfortunately the philosophy of Ayn Rand is like a cancer. I find that this point of view, with its pseudo social darwinism, has a revolting effect upon the personalities of those who adopt it, making them less humane, less compassionate. I, for one, cannot live like that.
I am further not convinced by any of the arguments for morality given by secular thinkers such as Sam Harris or even Derek Parfit. These arguments are all invalid. Morality has to start from somewhere, somewhere within the compassion for human suffering within a person. Good and Bad are not facts like one finds in science. Thus it will always be prone to the kind of controversy in which we currently find it. I can't justify my own ethics. My point of view is just the point of view I have adopted, for personal, psychological reasons.
In my opinion the best way to live my life is described in the Tao Te Ching and the writings of Epictetus. I suggest that everyone read these two texts. Others will adopt other points of view. As far as economics are concerned, I think something like a mixed economy has more going for it than either communism or untrammeled capitalism. Large capital will always corrupt government, so the ideal of pure capitalism is unreachable, even if it were the most likely to produce freedom, which I doubt.. Communism gives rise to the concentration of power in the hands of an elite. I also suspect that democratic socialism is doomed to failure as an ideology; competition and acquisitiveness are ineluctable as forces of nature. I don't think we currently have a good single solution to the fundamental economic problems of the world.
One thing I will say is that religion will not produce the answer to human problems. I am aligned with those who see religion as a pernicious influence. It creates in groups and out groups. It institutes irrational laws like sharia. It attempts to steal the freedoms of those considered 'sinners'. All based on irrational adherance to ancient texts written by primitive people ignorant of the advances since the Scientific Revolution.
It is time to put gods aside. In my view a careful examination of theological arguments leads to the conclusion, with high probability, that there is no god at all. We also need to avoid the irrational ideologies that can arise in an atheist worldview.