Below is an easy-to-play PDF that makes playing the chords for the hymn “Grace Greater than Our Sins” pretty simple. The diagrams show how to strum the first four measures of the song. The rest of the song has the same duration notes.
Strum the G chord in this measure 3 times, counting the rhythm as shown above the three slash marks.
Change to a D chord in time to strum it on beat 1 of this measure and strum it again on beats 2 and 3.
Change back to a G chord in time to strum it on beat 1 of measure 3 and hold it for two beats. Strum the G again on beat 3.
Strum a G chord on beat 1 of measure 4 and hold it for 3 beats.
Now you should know how to play the chords for the whole song, as shown by the chord diagrams and slashes in this PDF!
Practice playing the chords to the melody: