Unlike great britain and many other nations, the united states does not have an church that is officially supported by the government and recognized as a national institution.

The correct answer should be something like established

That is because the first amendment has the "anti establishment" clause where it is prohibited for the church to establish any church, which means that the government or the country can never give tax-payer money to fund churches or choose which church is the official one or anything similar because all people in America are equal regardless of religion.