HOW does the existence of the Universe make those who do not worship God to be "without excuse"?

>"For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who by their unrighteousness suppress the truth. For what can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse." (Romans 1:18-20, ESV) The Apostle Paul here says that those who ignore God, who fail to worship him or give him thanks are without excuse because the Universe shows there is a Creator God with certain attributes, namely, that he is eternal and has a divine nature. My question is, in what way(s) does the existence of the Universe plainly demonstrate the existence and nature of God? Preferably, in your answer say what "eternal power" means, and show how the Universe demonstrates the eternal power of God? My question seeks answers mainly from a Trinitarian perspective. (If you answer from other perspectives please indicate this in your answer. Thanks.)