And these signs - These miracles. These evidences that they are sent from God.
Them that believe - The apostles, and those in the primitive age who were endowed with like power. This promise was fulfilled if it can be shown that these signs followed in the case of any who believed, and it is not necessary to suppose that they would follow in the case of all. The meaning is, that they would be the result of faith, or of the belief of the gospel. It is true that they were. These signs were shown in the case of the apostles and early Christians. The infidel cannot say that the promise has not been fulfilled unless he can show that this never occurred; the Christian should be satisfied that the promise was fulfilled if these miracles were ever actually wrought, though they do not occur now; and the believer now should not expect a miracle in his case. Miracles were necessary for the establishment of religion in the world; they are not necessary for its continuance now.
In my name - By my authority, and using the power that I would in such cases, if bodily present. This was done; and in this they differed essentially from the manner in which Jesus himself wrought miracles. He did it in “his own name,” and as possessing original, underived authority. See the account of his stilling the sea (Matthew 8:26, etc.); of his healing the sick Matthew 9:5-6; of his raising Lazarus, John 11. The prophets spoke “in the name of the Lord.” The apostles did likewise, Acts 3:6, etc. There was, therefore, an important difference between Jesus and all the other messengers that God has sent into the world. He acted in his own name; they in the name of another. He wielded his own power; they were the instruments by which God put forth the omnipotence of his arm to save. He was therefore God; they were men of like passions as other men, Acts 14:15.
Shall they cast out devils - See the notes at Matthew 4:24. Compare Acts 16:16-18.
Shall speak with new tongues - Shall speak other languages than their native language. This was remarkably fulfilled on the day of Pentecost, Acts 2:4-11. It existed, also, in other places. See 1 Corinthians 12:10.