The image of God must mean something other than our physical body being an image, for after all, God is Spirit.
So, here are three ways which I think we are an image of God.
1. As God has dominion/authority over the universe; man was to be in the image of God, and have dominion/authority over the earth.
2. As God is a moral and righteous being; man was to be in the moral image of God, knowing right from wrong, and choosing to do right.
3. As God created through speech ("God said let there be light, etc.";) man was to be in the image of God also creating through speech, although in a different manner. Man was to use speech in creating names for the animals, making categorizations, expressing idea, etc.
So, here is my thought on #3. We must realize and have appreciation for the sanctity of speech; that as God’s speech is Holy, we should maintain our speech in a Holy manner; we should never ever lie. Every time we lie, we tarnish our image of God. E.g., Acts 5:4 when we lie, we lie to God, in whose image we are made.