Although this is the intro to the song, the it is played throughout in the background:
[ Tab from: https://www.guitartabs.cc/tabs/t/tobymac/atmosphere_tab.html ]
e|--------7-------0--------3-----3-----3-----3------|
B|--------5-------5----------5-----5-----5-----5----|
G|--------5-------5------------4-----4-----4-----4--|
D|--------------------------------------------------|
A|--------------------------------------------------|
E|--------------------------------------------------|
it's played on the recording with a clasical guitar, so it sounds a little different
a normal steel stringed one.