Of course you can't portray God, nobody knows what he looks like! But many of us have images to worship or to remind us that we are mortals. Religions are the primary and most important source of all art, wherever you are, whatever your background or culture is.

Sometimes we can cry when we look at a photo. For instance a picture of someone important to us.
We don't get emotional because we look at a piece of paper, but because what it represents. Because of that we may put a nice frame on it, place it somewhere special. We may even put a flower next to it, or a candle.

We may even go so far as to worship it, that is the idea it represent, not the thing itself, In Hinduism it is called 'darshana', Hindus look beyond the thing itself.
In Christianity this may be a little different: "This is the blood of Christ"

In Gambia (West Africa) I got this wooden sculpture from a young streetseller. He had it standing against a tree and it had obviously a special meaning to him (as it has for me know). He was only willing to part with it because I also bought a beautiful handcarved mask. Earning some money was more important for him.