SS, interesting thread and food for thought. I reason this way. Say a planet has all the ingredients to sustain life, an atmosphere, a moderate climate, lots of water, fertile soil, rich in all kinds of minerals, etc. All the best scientists on earth are invited to go there. Their spaceship has the best that technology has to offer. They are invited to do terra forming with only one precondition. They have to start from scratch. They are allowed to take with them all the elements of the periodic table. They have to create organic matter from inorganic matter. Then they have incorporate organic matter into living systems which would be able to reproduce successfully. They can start with microoganisms and plants. Then they can advance to more complex animals.
At this stage such a mission would be impossible, even if they had a million years at their disposal. The scientists would rather take with them existing plants and animals, tried and tested systems, and turn these into successful ecosystems. So, modern science has serious limitations. Perhaps advances would bring them to a point where they can attempt such a mission, but at this stage it lies in the realm of science fiction. When mankind have reached that point, they can jettison religion. They have become "gods." But not before then.