Final answer:
The line from Jonathan Edwards' 'Sinners in the Hands of an Angry God' that supports the thesis of his preaching awakening people to return to God is the one highlighting God's anger towards those at ease in the congregation.
Step-by-step explanation:
If Jonathan Edwards' powerful sermons were used to awaken and bring people back to the church and to God, certain lines from his sermon Sinners in the Hands of an Angry God would effectively support this thesis.
The line from Jonathan Edwards' 'Sinners in the Hands of an Angry God' that supports the thesis of his preaching awakening people to return to God is the one highlighting God's anger towards those at ease in the congregation.
Considering the vivid imagery and dire warnings he presents, the line "...God is a great deal more angry with... many, in this congregation, who it may be are at ease" illustrates the urgent need for spiritual awakening that Edwards saw in his congregation.
This line, along with others from his sermon, echoes his intent to shake complacent individuals into recognizing their need for divine help and to rouse them to action in pursuit of salvation.