There are things about God that people cannot see—his eternal power and all that makes him God. But since the beginning of the world, those things have been easy for people to understand. They are made clear in what God has made. So people have no excuse for the evil they do.
Look up to the skies. Who created all those stars? Who created all those “armies” in the sky? Who knows every star by name? He is very strong and powerful, so not one of these stars is lost.
Those who are not Jews don’t have the law. But when they naturally do what the law commands without even knowing the law, then they are their own law. This is true even though they don’t have the written law.