Some people consider it to be blasphemous to say that you are God. If you believe in concept of 'blasphemy', I say it is more blasphemous not to acknowledge it.
We often say we are children of God, or that God is in us somewhere. Think about it: God is omnipresent. He is not only watching everything like an old pervert - he IS everything and experiences everything through the wholeness of his creation. Saying 'you are God' acknowledges a person both as a human being and a divine expression of God. This is the basic reality of the universe.
You are God, whether you are aware of it or not. You can try to reject God by rejecting the power, beauty and responsibility of yourself as a human being, but that lessens only your own perception of yourself - you are still a beautiful part of God in God's eyes.
While many religions preach that God is outside of us, there are also many religions and philosophies which accept that we and the whole world is part of God. Perhaps the most famous is the phrase "tat tvam asi" from Vedantic Hinduism, along with the word 'Tao' from Taoist philosophy. In literal translation 'tat tvam asi' means 'that which you are'. (In English, the archaic way of saying "you are God" is "thou art God".)
Remember that you are not only a human personality in a human body with human weaknesses, but also a divine expression of God. Treat yourself and others with the Love and respect that we all deserve.