Watch the Higher Ground - 5 online guitar lesson by Richard Kiser from Gospel Fingerstyle Guitar
Once again, the chorus is built around basic chords so the first thing to practice is the chord progression of the chorus before you actually begin to play the melody. Then play the melody and try to play it while holding the chord that is relative to the melody at the time. Be sure and play this melody with your fingers. If you do this before you practice the bass line, it may be a bit easier to keep it flowing smoothly. Then add the bass line playing it with your thumb. Be sure and practice playing it very slowly at first, wile focusing on keeping the bass in sync with the melody. You will soon see that your thumb playing alternating bass will become second nature.