Two great questions underlie all philosophy and religion: they were often debated at the Areopagus in Athens, the ancient court of ideas and religion.  The questions are 'Who am I, and why am I here?’, and 'Who is God and what does He want of me?'  Paul answered both as he addressed the top religious philosophers in the world of his day.

Athens specialised in inert idols to be worshipped (Acts 17:16).  But the true God can never be a humanly shaped lump of stone or casting of precious metal, because He made the craftsmen who made the idols (Psalm 115:3-8).  No: God is a living personality who is far superior to us.  He has made us; we cannot make Him, nor is He made like us.  No: we are His offspring, having some of His characteristics, however much they have been spoiled.  Like a son in a family business, we are created to represent our Father, and work in His kingdom with Him.

To worship anything, which is not the true living God, is highly offensive to Him.  Before Jesus came, God was longsuffering with rebellious humanity, but now Jesus has provided a way to be forgiven.  That is why God demands that everybody must repent.  This is not an option but a command, which will be backed up when Jesus returns as the Judge of all humanity.  We know that He has the authority to judge, because God raised Him to life after being killed by those who rejected Him.

So to answer the questions: I am made in the image of God to represent Him, working with Him and for Him in this world.  God is the creator of everything and is in no way shaped by me.  Because I am prone to worship idols (anything that occupies my time, thinking and resources more than the true God) God commands me to repent, now.  If I do not, then He has the last word as my judge.  Repentance is the normal and essential response to realising my moral failure before a holy God.  The closer I am to Him, the more I see the contrast between my sinfulness and His purity; and the more I see the need to repent.  That is not a morbid introspection, but reality through which God wants to pour out His forgiveness as I repent.