Which when the apostles, Barnabas and Paul, heard of, they rent their clothes, and ran in among the people, crying out, Acts 14:14
Tearing the clothes and cutting the hair in mourning is very common among Semitic people. When they receive sad news, as of the death of relatives, men tear their clothes and women cut their hair as a token of mourning and grief. This custom still prevails among the Arabs, Jews, Assyrians, and Kurds.
Likewise when a man is accused of treason, he tears his garments, in order to prove his innocence and as a protest. In such cases the tearing of garments indicates humiliation. When a person is humbled and severely punished, he is stripped of all or part of his clothes. When governors, noblemen and officials are demoted or dismissed on charges of treason and disloyalty, the royal robes, rings and other tokens of authority are taken from them. In some instances, the giver of the garment takes it from the body of the person who has been accused and tears it in pieces.
On the other hand, insane persons nearly always walk about naked. Mourners and accused men often become very violent and act insane. In most cases, the garment is ripped open in front from the neck down. Noblemen and kings tear only a small part of their garment. David and all the men who were with him tore their garments when they were informed of the death of Saul and Jonathan (Sam. 1:11). At times mourners are prevented by friends from tearing their garments. Some mourners therefore wait until their friends arrive before they try to tear their garments.
Paul and Barnabas tore their garments as a protest against those who proclaimed them gods. By tearing their garments, they emphatically declined the honor of being gods, proving that they were men. Gods have no garments to tear, nor do they act like crazy men. Paul and Barnabas wanted to show that they were human beings like everyone else. Had they not done this, they would have been charged with treason by both the state and religious authorities for posing as gods.
Paul knew the temper of the Eastern people. He knew that such acts would not be tolerated by the priests and people in general. The crowd was moved by his speech, but the enthusiasm would not last long. On the other hand, Paul and Barnabas were preaching about the God of heaven and earth; they could not have accepted any honor that was contrary to the gospel of Christ.
(Lamsa, George. New Testament Commentary, A.J. Holman Co., Philadelphia: 1945, pgs 103-104)