God is: love, spirit, light (from Bible).

Why is light a defining characteristic of God?
- He's holy & pure
- unchanging, doesn't fail His promises, consistent
- nothing to hide - darkness often used to hide bad things, no darkness in God
- He exposes evil & sin (Prov 15:3)

Why is Jesus the true light? (v.5 THE light, v.9 the TRUE light)
- He's God manifested in the flesh (see beginning of Hebrews)
- John the Baptist came to bear witness to the light (v.7)

What does the light do to us?
- exposes our sin - through our conscience we know what sin is, through comparison with Jesus
- cleanses us

How do people respond to light?
- many reject it (v.5, v.11)
- many accept it (v.12)