If secular humanism is the idea that man is the ultimate in a world governed by the physical world and the limitations that accords, cosmic humanism is the idea that man is the ultimate in a world governed by the spiritual world and the lack of limitations that affords.
Cosmic humanism is not necessarily the hair-brained theories and contradictory myths that may first come to mind - hippies on drugs and inter-dimensional hocus-pocus, crystals and dream-catchers. Some forms of cosmic humanism are more mild and logical. It is the idea that this world is not the ultimate reality, that there is something substantially more out there that is not limited to our 3-dimensional constructs.
Some would say that the physical is a construct of our imagination, a mere illusion that we trap ourselves in that we must overcome to become enlightened. As the spiritual is superior to the physical, knowledge is the ultimate goal of life. If, they believe, you obtain true knowledge, you gain true power, even power over the physical world (as it is a mere illusion).
This ultimate knowledge is knowledge of what is. It is ultimate truth, some would say, it is god.
Cosmic humanists can become attached to the physical world, but their main objective is to become one with the spiritual. To pass over the physical into the ultimate reality that exists outside of the physical realm.
Christianity rests between the secular and the spiritual. We live in a constant balance between the physical and spiritual but the main difference is that we do not place man at the center of our worldview, we place Jesus there. Jesus is the ultimate, not man. It is about Him, not us. Humanism, both secular and cosmic place their trust in man and in their own self, that is where they go wrong. They rely on themselves to get themselves out of the mess they themselves put themselves in. Do you see where they run into trouble?
The great eastern parable of the blind men feeling the elephant and each one saying the elephant is like something different has a stunning application here. The eastern mystic would say that in the parable, he is the prince who looks over at the blind men and say, each of you has a part of the truth, and thus all of you are partially correct. But in reality, all the religions are the blind men, looking to save themselves by their own effort, defining for themselves what the elephant looks like, while Christianity looks away from man and says it is not about us, but about Him, and He (the one who can see) says it is so. This is what an elephant is. Is that close minded? Only if I reject to hearing the evidence of opposing viewpoints. I am open to hearing such, but keep this in mind when talking about open/closed mindedness:
“The purpose of having an open mind, like having an open mouth, is to close it on something solid.” ~ G. K. Chesterton.