Anger is extreme displeasure. Anger is not always intense and it is not always seen outwardly. If anger goes uncontrolled it is usually manifested by lashing out at others. If anger is controlled correctly it can be beneficial, just as Jesus angered when he saw the money changers in the temple.
15 And they come to Jerusalem: and Jesus went into the temple, and began to cast out them that sold and bought in the temple, and overthrew the tables of the moneychangers, and the seats of them that sold doves;
16 And would not suffer that any man should carry any vessel through the temple.
17 And he taught, saying unto them, Is it not written, My house shall be called of all nations the house of prayer? but ye have made it a den of thieves. (Mar 11:15-17 KJV)
What Jesus felt was a righteous indignation. Jesus was angry, but he did not sin. Paul talks about being angry, yet not sinning.
Be ye angry, and sin not: let not the sun go down upon your wrath: (Eph 4:26 KJV)
Anger can be used for a good purpose, but it is not good to hold on to anger or to have anger without cause.
But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire. (Mat 5:22 KJV)
We must have temperance over our actions and emotions.
22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
23 Meekness, temperance: against such there is no law. (Gal 5:22-23 KJV)
Use anger to combat false doctrine and contend for the faith, but keep a good attitude toward others. Keep everything in proper perspective and use anger to your advantage. Do not lash out at others because it is not people you are contending against; it is their doctrine. Keep the Fruit of the Spirit toward others at all times and when you must anger… sin not.