Deity, Revelation, Extension

As Descartes' ample attention to the topic indicates, the salient characteristic of the concept of Deity to which he subscribes is that its existence needs to be proven, i. e. a characteristic of many other rival concepts is that it is to be feared, which implies that its existence is not in doubt.  Now, the need for a proof of it seems to presuppose that existence is not easily apparent, one reason of which might be that the Deity is noumenal, e. g. Platonist.  However, Descartes' concept entails the possibility of revelation, and, thus, that the Deity contingently appears. But, then, the problem is to reconcile that property with another--non-extension, a topic which Descartes' seems to leave unaddressed.