The Masculinity of God
When God created the world he was already masculine. He is our father, not our mother.
He was masculine but not male. The sexes only occur within our world. Elsewhere we explain how sex epitomises gender, but here we are not describing our world's workings or destiny, only its original and unchanging relationship with God.
In other words, his primary relationship with us is creative, not preservative.
His "feminine side" is secondary.
Until the late 20th century, those who held that the world was created intentionally (rather than emerging spontaneously from a "primordial chaos" or "cosmic womb") usually took its creator's masculinity as self-evident, and authors of creeds saw no need to mention it.
But now that the idea that each sex can and should do everything that the other does is so prevalent that God's masculinity needs to be highlighted.
For more details on God's nature, see The Trinity.