Why didn't the Buddha speak about God and the soul?

The Four Noble Truths and Eight Noble Paths are the main principles of the Buddha and every person can be a Buddha if he/she follows these principles. As far as I've heard the Buddha didn't believe in the existence of God, in the immortality of the soul, and the soul itself. - Was the reason why the Buddha didn't speak about God and the soul, because he couldn't provide the proof for it? - He wanted to be more practical than theoretical (so that the practicality ultimately leads one to believe in God and soul)? - He wanted to attract the atheists to Buddhism? Please what is the truth behind it?