Romans 1

For since the creation of the world His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and Godhead, so that they are without excuse, because, although they knew God, they did not glorify Him as God, nor were thankful, but became futile in their thoughts, and their foolish hearts were darkened.  Professing to be wise, they became fools, and changed the glory of the incorruptible God into an image made like corruptible man—and birds and four-footed animals and creeping things. vv.20-23

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Everyone knows there's a god even if they've never seen a Bible or heard of the creator. Creation clearly shows there's an intelligent designer behind it all that even evolutionist marvel-whether they give someone or something the glory instead of God Himself.  Through creation God's invisible attributes are clearly seen (seems like an oxymoron, but this is understood by the things that are made as a result).  The Greek word for see here is intensified that means we don't just see but "see down to the core."  This is said to show that men are without excuse.  Without excuse that they never had the chance to wonder about the Creator.  Yet many choose to go from adoration to speculation.  People have to actively choose not to believe in God.  And doing this they have actually become fools rather than wise.  I wonder what men of the past knew that today many think man came from apes or a swamp or a rock.  Paul is speaking to Jews that lived in Rome who knew God on a more intimate level than the nations, so are held at a higher standard. 
How do you see God in creation?  How do you think others can know the true God without having a Bible?