Is there a righteous indignation (anger) that is without sin?
Ephesians 4:26 (NKJV) “Be angry, and do not sin”: do not let the sun go down on your wrath,"
"As Moses came down from the mountain with the two tables of the testimony in his hand, he heard the shouts of the people, and as he came near, he beheld the idol and the reveling multitude. Overwhelmed with horror and indignation that God had been so dishonored, and that the people had broken their solemn covenant with him, he cast the tables of stone upon the ground, and broke them. Though his love for Israel was so great that he was willing to lay down his own life for the people, his zeal for the glory of God moved him to anger, which found expression in this act of such terrible significance. God did not rebuke him. The breaking of the tables of stone was but a representation of the fact that Israel had broken the covenant which they had recently made with God. His anger was not prompted by self-love or wounded ambition, but was that righteous indignation against sin, which springs from zeal for the glory of God, and which is referred to in the words of Scripture, “Be ye angry, and sin not.” {RH September 1, 1896, par. 7}
"It is true there is an indignation that is justifiable, even in the followers of Christ. When they see that God is dishonored, and His service brought into disrepute, when they see the innocent oppressed, a righteous indignation stirs the soul. Such anger, born of sensitive morals, is not a sin. But those who at any supposed provocation feel at liberty to indulge anger or resentment are opening the heart to Satan. Bitterness and animosity must be banished from the soul if we would be in harmony with heaven." {DA 310.4}
"Christ’s indignation was directed against the hypocrisy, the gross sins, by which men were destroying their own souls, deceiving the people and dishonoring God. In the specious deceptive reasoning of the priests and rulers He discerned the working of satanic agencies. Keen and searching had been His denunciation of sin, but He spoke no words of retaliation. He had a holy wrath against the prince of darkness, but He manifested no irritated temper. So the Christian who lives in harmony with God, possessing the sweet attributes of love and mercy, will feel a righteous indignation against sin; but he will not be roused by passion to revile those who revile him. Even in meeting those who are moved by a power from beneath to maintain falsehood, in Christ he will still preserve calmness and self-possession.—The Desire of Ages, 619, 620 (1898)." {2MCP 517.2}
Unless indicated otherwise, quotations come from the writings of Mrs. Ellen G. White.