Statistics
The latest Harris Poll came up with 79% 'believing in God', 66% 'absolutely believing in God' (USA). These numbers are a tad lower than Pew's site, generally acknowledged as a premier research site, but Pew's is based on annual statistics.
36% attend a worship service once monthly
26% attend a worship service once weekly
A look at any breakdown on this type of information reveals what one would expect, concentrations of believers and worshipers are prominent in the Lower Midwest and South. Numbers of active believers and worshipers are heavily weighed in middle-aged and retired groups, higher education being an obvious factor in lessening dependence on mythology in younger (under 30) age groups.
The US being a 'new' country and somewhat geographically isolated, dependence on Christianity as a belief system has slowly declined on a steady basis, which is predicted to continue and accelerate as higher education becomes even more widespread, much as what has transpired in developed European countries. Most studies indicate that Christianity will no longer be a dominant factor in US life styles by 2030 as younger, better educated generations replace older, less educated, tradition minded citizens.
Things will, as usual, change.