Whether God's mercy suffers at least men to be punished eternally?

Objections

Objection 1 : It would seem that God's mercy does not suffer at least men to be punished eternally. For it is written (Gn. 6:3): "My spirit shall not remain in man for ever because he is flesh"; where "spirit" denotes indignation, as a gloss observes. Therefore, since God's indignation is not distinct from His punishment, man will not be punished eternally.
Objection 2 : Further, the charity of the saints in this life makes them pray for their enemies. Now they will have more perfect charity in that life. Therefore they will pray then for their enemies who are damned. But the prayers of the saints cannot be in vain, since they are most acceptable to God. Therefore at the saints' prayers the Divine mercy will in time deliver the damned from their punishment.
Objection 3 : Further, God's foretelling of the punishment of the damned belongs to the prophecy of commination. Now the prophecy of commination is not always fulfilled: as appears from what was said of the destruction of Nineve (Jonas 3); and yet it was not destroyed as foretold by the prophet, who also was troubled for that very reason (Jonas 4:1). Therefore it would seem that much more will the threat of eternal punishment be commuted by God's mercy for a more lenient punishment, when this will be able to give sorrow to none but joy to all.
Objection 4 : Further, the words of Ps. 76:8 are to the point, where it is said: "Will God then be angry for ever? [*Vulg.: 'Will God then cast off for ever?']" But God's anger is His punishment. Therefore, etc.
Objection 5 : Further, a gloss on Is. 14:19, "But thou art cast out," etc. says: "Even though all souls shall have rest at last, thou never shalt": and it refers to the devil. Therefore it would seem that all human souls shall at length have rest from their pains.