Dark energy is a term used by scientists who are trying to make sense of evidence that things are even more complicated than they thought. Basically it's a marker saying, "watch this space." The word "notion" doesn't imply casting doubt on the observations, but recognising the degree of uncertainty which scientists feel tabout how to make sense of them.

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"Creationism" and "intelligent design" both share a belief in "God" as the shaper of the world. But formally they start from different places. "Creationism" starts from a belief in God, and from a literal belief in an interpretation of ancient writings, whereas "intelligent design" starts at least formally from consideration of scientific evidence, and draws from
this the conclusion that the explanation for this is an intelligent designer, in other words "God".

So far as issues around life is concerned the counter explanation is that with sufficient time, random association of molecules is adequate to explain the development of pre-life to life, and natural selection sufficient to account for everything else. So far as issues around the "fine-tuning" of the universe one suggested explanation is the existence of an enormous number of universes, so that the unlikely things that allow a life-bearing universe have the chance to occur. And others argue that the "fine-tuning" is a misunderstanding. There is no consensus.

The point is, this is about interpretation of evidence.