"The terrible Avenger is to be praised, as well as the loving Redeemer. Against this the sympathy of man's evil heart with sin rebels; it cries out for an effeminate God in whom pity has strangled justice. The well-instructed servants of Jehovah praise him in all the aspects of his character, whether terrible or tender. Grace streaming from the mercy-seat can alone work in us this admirable frame of mind." Charles Haddon Spurgeon, Treasury Of David, Psalm XCIX

And for an insight into Jehovah's character when he is terrible, observe...

"And Jesus went into the temple of God, and cast out all them that sold and bought in the temple, and overthrew the tables of the moneychangers, and the seats of them that sold doves, And said unto them, It is written, My house shall be called the house of prayer; but ye have made it a den of thieves." Matthew 21:12-13

"...and Jesus went up to Jerusalem, And found in the temple those that sold oxen and sheep and doves, and the changers of money sitting: And when he had made a scourge of small cords, he drove them all out of the temple, and the sheep, and the oxen; and poured out the changers' money, and overthrew the tables; And said unto them that sold doves, Take these things hence; make not my Father's house an house of merchandise. And his disciples remembered that it was written, The zeal of thine house hath eaten me up. Then answered the Jews and said unto him, What sign shewest thou unto us, seeing that thou doest these things? Jesus answered and said unto them, Destroy this temple, and in three days I will raise it up. Then said the Jews, Forty and six years was this temple in building, and wilt thou rear it up in three days? But he spake of the temple of his body. When therefore he was risen from the dead, his disciples remembered that he had said this unto them; and they believed the scripture, and the word which Jesus had said." John 2:13-22