GD:
That's my point. It's intentionally not the other way around.
Alan nailed it when he highlighted that it's about "substance". There are other scriptures which make the same point, that Jesus was of the same substance as the Father.
If Christendom wasn't so knee-jerk against the concern of being labelled polytheistic, it might accept a triune family of Father / Mother / Son.
The next step of quantifying what "substance" this family is made of becomes the link needed to the Trinity doctrine. Godstuff (allegedly) is eternal and everywhere, simultaneously, regardless of which person is made of it.
Another step again, whioch would be anathema to most Christian religions, is the idea that if this godstuff is everywhere, then it must inhabit every molecule of us and the rest of nature - pantheistic, almost.