Godliness is a mystery- means what God does is a mystery:
Ecc 3:
10I have seen the burden God has laid on the human race.
11He has made everything beautiful in its time. He has also set eternity in the human heart; yet
a no one can fathom what God has done from beginning to end.
But God Himself is not a mystery:
Acts 17:
24“The God who made the world and everything in it is the Lord of heaven and earth and does not live in temples built by human hands.
25And he is not served by human hands, as if he needed anything. Rather, he himself gives everyone life and breath and everything else.
26From one man he made all the nations, that they should inhabit the whole earth; and he marked out their appointed times in history and the boundaries of their lands.
27God did this so that they would seek him and perhaps reach out for him and find him, though he is not far from any one of us. 28‘For in him we live and move and have our being.’
b As some of your own poets have said, ‘We are his offspring.’
c
29“Therefore since we are God’s offspring, we should not think that the divine being is like gold or silver or stone—an image made by human design and skill.
Q. How is God a mystery if He is working hard for us to know Him?