Yes, true Christians should work hard to make America a Christian nation in name and in practice.
In other words, the United States of America should be de jure and de facto Christian nation. Look at the above video to understand the concepts of de jure and de facto.
It is important for Christians to inform themselves about public policy matters and use public policy practices to advance Christianity in America.
It is important for Christians to consciously shift public policy away from religiously pluralistic society to a Christian American society.
The Puritans wanted America to be a distinctively a Christian society. And so did the Founding Fathers of America.
Laws need to be interpreted and created that support distinctively a Christian nation.
It is important to block out immigration from people of other religions, because increase in the number of people of other religions will dilute the Christian identity of the United States of America.
In other words, policy and laws must be changed in order to preserve the Christian identity of America.