Basque ancient religion has many genies but only two Gods: Mari and Sugaar (or Maju). They are the divine couple and can well be considered a single dual God. They are the personified Yin and Yang.
What about Urtzi? Urtzi has no mythology. It can well be thought as a mere abstract personification of the Sky, much like Chinese Tian, that eventually absorbed foreign celestial deities like Zeus or Yaveh.
This dual monotheism that pre-dates polytheism is also found in other cultures:
In Daoism: Yin and Yang, fundamental principles of the Universe (not properly gods though, as they are not personified)
Some variants of Hinduism also seem to believe in this male-female dualistic monotheism: some forms of Shaivism, all of Shaktism and the related schools known as Tantra.
Guess that for monofisite religions such as Judaism, Islam and some oriental Christian churches the concept of a dual God is kind of perplexing, but it shouldn't be so for mainstream trinitarian Christianism, withe their triple God. And certainly dual monotheism it's both much more intuitive and self-explanatory than the male-only Trinity and seemingly much older.
From the primordial Chaos sprang both Gaia, the Earth, and Eros, the force of Life. This belief, described by Hesiodos at the beginning of his Theogony, seems to be deeply rooted in Europe and the Mediterranean, dating to at least Neolithic times.
Forget about that fancy Judaic story of creation in six days, forget about any need to introduce intelligent design, not in science classes, but in your personal philosophy. The dual God does not create once but always: perpetual creation is the real thing.
But my holy book says...
Ah, you idol worshipper of words! Do you think that God only manifests in one particular book or act, or is it actually doing every time and in everything.
Your god is false... or rather a very narrow version of the real thing. Evolution definitively works better than any concievable ID and the Gods certainly know better than trying to intervene: they instead participate of the perpetual creation and change. They are the World, including you and I.
The cosmic dance is for real, your petty book is just part, a small part, of it.
Mari and Sugaar are said to meet every Friday and in such celebrated meetings they create the storms, that fertilize the land.
It's not just some distant friday in the far past... it's every week, actually maybe every single day, hour, minute, second and even Plank time.