The son could only talk to his father in the sister's absence? Despite the ostensible 'answer' given at the end that God exists in the form of love, the film is full of ambiguities, as all the characters' reliability remain in question till the end.
Poor Minus, young but forced to face the reality. Loved Minus, Papa spoke to him. It seems that it is not so important to recognize the power of god or that of love. what really important is love always exists and all kinds of love exist, the most absurd and the most sublime, the trust or the distrust, love is the proof of God.