The Phalangist party declined an invitation to be involved in the 30-minister government and is the only main political group that will not be involved in running the country.
Prime Minister Saad Hariri said he had offered Phalangist a minister of state post but the party rejected.
Officials at the party were said to be unhappy at the nature of the offer which they viewed to be a junior role in the government.
Sources suggest they were only offered one post while other parties were given several.
Despite the Christian party not being involved the PM called it a "government of entente".
