You can use Tag Search for this. All pages have tags, which are keywords that describe some aspect of the article. There are broad tags, such as scp, character and so on, and more specific tags such as memetic, cognitohazard, and the like. Here is a (very, very) comprehensive list of all available tags. Although there's no god tag, god-esque SCPs tend to be defined under ontokinetic (reality bending), so my recommendation would be to start there.
That being said, and speaking as a reviewer, my recommendation would be to not worry too much about conceptual overlap. There's always going to be overlap when articles are reduced down to simple keywords, like god. Considering the wiki's current stance as a creative writing site, it shouldn't matter if my banana SCP is invalidated because someone already wrote a banana SCP in 2014. What really matters is that you're trying to tell your own story, and trying to do something different in your own style. If you think about it that way, there's a very low chance that conceptual overlap will occur.
Of course, there's still a chance. But, at the end of the day, that is what the Idea Critique Forums are made for. If you've done your scouring and are still unsure, you can make a post asking for feedback and advice on whether the concept has been done previously.