They'll Know We Are Christians:
Jars of Clay plays the intro on a Banjo but
I have also seen them play it on guitar.  It sounds good.
Banjo intro:

E----------------------------------|
B----------------------------------|
G----10------10-----10----10-------|
D-------12------12----12----12-----|
A-12-------12-----12----12---------|
E----------------------------------|

E--------------------------------------|
B--------------------------------------|
G---3---3---3----3---------------------|
D--5---5---5----5----------------------|
-A-5---5---5----5----------------------|
E--------------------------------------|

Chords:
 DmWe (xx0231@1)are one in the Spirit
 GmWe (355333@1)are one in the Lord
 DmWe (xx0231@1)are one in the Spirit
 GmWe (355333@1)are one in the Lord
Dm (xx0231@1)                        GmAnd (355333@1)we pray that our unity may one day be restored
Bb (x1333x@1)                              DmAnd (xx0231@1)they'll know we are Christians by our love, by our love
     Gm (355333@1)                              DmThey (xx0231@1)will know we are Christians by our love

Guitar:
Dm (xx0231@1)              DmBanjo: (xx0231@1)E----------------------------------|
B----------------------------------|
G----10------10-----10----10-------|
D-------12------12----12----12-----|
A-12-------12-----12----12---------|
E----------------------------------|
Guitar:
Gm (355333@1)              DmBanjo: (xx0231@1)E--------------------------------------|
B--------------------------------------|
G---3---3---3----3---------------------|
D--5---5---5----5----------------------|
-A-5---5---5----5----------------------|
E--------------------------------------|
 DmWe (xx0231@1)will work with each other
 GmWe (355333@1)will work side by side
 DmWe (xx0231@1)will work with each other
 GmWe (355333@1)will work side by side
 DmAnd (xx0231@1)we'll guard each mans dignity
 GmAnd (355333@1)sing each mans pride
Bb (x1333x@1)                              DmAnd (xx0231@1)they'll know we are Christians by our love by our love
     Gm (355333@1)                               DmYea (xx0231@1)they'll know we are Christians by our love

Guitar:
Dm (xx0231@1)              DmBanjo: (xx0231@1)E----------------------------------|
B----------------------------------|
G----10------10-----10----10-------|
D-------12------12----12----12-----|
A-12-------12-----12----12---------|
E----------------------------------|
Guitar:
Gm (355333@1)              DmBanjo: (xx0231@1)E--------------------------------------|
B--------------------------------------|
G---3---3---3----3---------------------|
D--5---5---5----5----------------------|
-A-5---5---5----5----------------------|
E--------------------------------------|

God Bless,
Byron