"For thou art an holy people unto the Lord thy God, and the Lord hath chosen thee to be a peculiar people unto himself, above all the nations that are upon the earth." (Deuteronomy 14:2)
If you are a believer in Jesus, then God has chosen you out of all people of the earth to be set apart for Himself, special and highly favored. A royal priesthood, a peculiar people (II Peter 2:9).
The children of Israel were far from perfect, yet in God's eyes they were the very object of His affection. He would destroy anyone who would threaten or harm them, even if they were "in the wrong," and bless those who would give them even so much as a cup of cold water (Genesis 12:3, Matthew 10:42).
God's system of fairness operates differently than ours. We judge based on circumstances and a natural perspective on equity and justice. However, God's judgment is based on covenant. I recently watched a documentary about a notorious Mafia family. The father was a feared and ruthless enforcer for one of the five Italian crime families, and his daughter was picked up every morning by a driver who took her to school (the driver was not associated with the mob at all, and knew nothing about the family). It was discovered that the driver had attempted to coerce the young, middle-school aged girl into performing a sexual act with him, and the next morning, several men met him by the car, pulled him out, took him to a secluded place and shot him dead. End of story. No trial, no opportunity for explanation. Why? Because he had touched something precious that belonged to them. The apple of their eye (Zechariah 2:8).
Now, I understand that these were wicked men, and that their actions outside of the law are inexcusable, however, they take care of their own. In a similar manner, our Heavenly Father is jealous over those who belong to Him. Of course God's justice is according to truth against those who would trouble us, but nevertheless, His judgments are fearful, holy, righteous, and true. It is a fearful thing to fall into the hands of the Living God (Matthew 18:6-7, Hebrews 10:31).
"Well that's not love, brother... How can you compare God with the Mafia?"
But it is love, a very special, jealous kind of love. God is jealous over His people, but we must seek the protection of our Father in order to partake of it rather than attempting to avenge ourselves. King Saul relentlessly sought after David's life, but David deferred judgment to the Lord, even when he had opportunity to take matters into his own hands (I Samuel 24:3-7, 26:7-11).
David understood covenant relationship, and He knew that God would honor His promises. He knew that he was better off committing his cause to the Lord rather than attempting to take care of matters himself (I Peter 2:23). God commands us to forgive, "turn the other cheek," love our enemies, and do good to those who persecute us, and for this reason it is commonly assumed that we are required to be "doormats," and to be trampled upon at the whim of every wicked man and device. But nothing could be further from the truth. When we forgive, and return blessing for evil, we defer our cause to our Heavenly Father. We give place unto wrath, if wrath is justified (Romans 12:19-20).
Of course, this requires faith on our part, trust, and suffering in the flesh (denying the fleshly impulse to handle situations ourselves), and holding grudges. We are to trust our Heavenly Father unequivocally, seeking His glory in all things. Much of the time mercy prevails, and God brings victory in unusual, wonderful, and glorious ways. However, our victory is always assured when we walk in God's ways and obey His commands.
We must understand that God is a God of love, but He is also a consuming fire (Hebrews 12:29). He is the defender of Israel, and protector of all who put their trust in Him (Isaiah 54:17).