The belief that The United States of America was founded on the ideals of Christianity is about as mythical as a man gathering the worlds animals on a boat and surviving a flood for forty days and forty nights. There is circumstantial evidence to prove that the United States was NOT found on values of Christianity, but moreover the values found in the philosophical writings of people like Immanuel Kant, Spinoza, and John Locke. More importantly, people who founded our nation such as Thomas Jefferson, Benjamin Franklin, and Thomas Paine had outspoken views against religion. Most of this Christian Nation bullshit came during the events of The Red Scare and The Civil War where scared Evangelical nutjobs came incredibly close to adding an amendment to The United States Constitution that would have recognized Christianity as the state religion of The United States of America.
Practice what you wish as the first amendment guarantees us Freedom to practice whatever religion we want. But also keep in mind that Freedom of Religion is equal to Freedom FROM Religion. Keep it out of MY government.