“Why would belief in an infinite and eternal Universe abnegate the existence of an equally infinite and eternal God?”
It wouldn’t, but it seems that in that model the Universe becomes an eternal and coequal partner with God - and there would be absolutely no way to say that God created it.
How can you create something that always was.
The God of the Bible is a God who created the universe, not one who exists coequal to it.
So whoever this God of an eternal universe might be - he isn’t the God of the Bible.
You have an awfully limited view of God.