Philosophy and science are disciplines or methods, whereas theism is mainly a model. A better comparison would be with religion rather than theism since religions have alternative methods (such as an emphasis on faith or ritual). As a model, theism is arguably outdated. For instance, your quotation says that theists attempt to "explain" the world, but science redefined what counts as a genuine explanation. Theism is a pseudo-explanation since the paradigm has changed, which again has likely made theism obsolete in those terms.