I can't say I've met any Christians in my daily life that follow that philosophy. The main thing I notice is many religious people I meet believe they are morally superior to other groups. There's a holier-than-thou attitude. If they are being taught that Christians are on the side of righteousness, then what does that say about the rest of us? Of course people will have a superiority complex when dealing with non-Christians because they believe they are on God's side and we are not. It doesn't matter if they are humble towards God if they aren't humble when dealing with other people.
Perhaps if what you say is the "true" Christian philosophy, then churches should start actually teaching more humility. I can't speak for all churches, but the few churches I attended when I was Christian failed to do that. The churches I went to basically taught that we were God's A-team.
MY DEAR BROTHER,
Humility and knowing/proclaiming/doing God's revealed Will are not contradictory or self-exclusionary ideals--they follow one from the other. The reason why atheists find this problematic is because, for an atheist, there are no moral absolutes--no higher Authority whose Will is Law in the universe He created.
A Christian--by definition "A follower of Christ--is an adherent to God's Laws for His universe as taught and demonstrated by His Son. i can see the temptation of those who neither believe that God exists or believe that absolute Morality--binding upon all--exists, could wrongfully judge those who have opposing views as having a "superiority complex." This, however, is a matter of perception (and, perhaps, even a few unacknowledged twinges of guilt) and not an accurate assessment of the situation.
In "modern" thinking, one person's situational moral standards are equally valid with those of another and "must" be respected as such. But in a God-governed Universe where, in fact, no such ideals of "valid personal moralities" have any basis in the reality of the situation, to assert the Truth is not evidence of a belief in the "superiority" of the holder of one belief system over the un-belief system of the other; it is evidence of Love and Compassion of Christians for those who are misguided and fatally mistaken in their beliefs, and a desire to save them from the consequences of their misunderstanding of reality and disbelief in the Truth.
This Truth MUST be told--whether or not it is accepted. Why? Because God said to do so. He also clearly reminds us of our humble status in the whole process, as Paul relates,
"For we do not preach ourselves, but Jesus Christ as Lord, AND OURSELVES AS YOUR SERVANTS FOR JESUS' SAKE. . . .BUT WE HAVE THIS TREASURE IN JARS OF CLAY TO SHOW THAT THIS ALL-SURPASSING POWER IS FROM GOD AND NOT FROM US." (II Corinthians 4:5;7)
What you describe in your above assessment of this Belief in Ultimates from your position of non-belief in either God or His Commandments by which Creation is ruled and judged, is similar to a drowning man yelling at those trying to throw him life perservers, "Hey, why are you acting like you are better than me?" The reply? "We are in no way "better than you, we are just standing on firmer ground."
As to how this Truth pertains to our country, John Adams, our second President, explains,
"We have no government armed with power capable of contending with human passions unbridled by morality and religion. Avarice, ambition, revenge, or gallantry, would break the strongest cords of our Constitution as a whale goes through a net. Our Constitution was made for a moral and religious people. It is wholly inadequate to the government of any other." It seems that we are learning this Truth the hard way, as we speak.

ABBA'S FOOL,
ephraim