Ideologies like Stalinism are similar to religion in that they both rely heavily on dogmatism over critical thinking.
Humanism is not based on objective reason either. It contains dogmas regarding 'human rights', etc. that are invented transcendent concepts with no basis in historical reality.
Valuing science and reason DOES lead to secular humanism. (Personally, I'd be interested in any counter-examples that you have.)
Tell that to the Enlightenment.
For example, Adam Smith's free market economics relies entirely on Divine Providence. Liberal economics is based on religion.
Locke argued that American 'Indians' didn't deserve land as they didn't commoditise it.
Jacobinism and French Revolutionary anti-religious murder, the 'cult of reason' etc. were based on science and reason.
Ditto Marxism
Scientific racism was a widely accepted product of the Enlightenment and we know where that led to.
There is no reason, and no evidence, that science and reason = secular humanism.
Humanism itself rests on the concept of human rights and humanity as a concept. These are cultural constructs that didn't exist prior to universal monotheism and its secular offshoots.
There is much evidence that secular humanism DOES lead to morally positive results, e.g. Scandinavia.
Again, this is not relevant to my point.