Cain showed he did not love God by deliberately giving Him half-hearted, unsuitable offering. Abel’s offering was from a pure heart filled with love for God.

Cain’s lack of love and fear for God was evidenced by his disobedience of God’s fatherly instruction (Gen. 4: 6-7). Obedience is the test of love. But we never heard that Abel was ever guilty of disobedience to God.

 Cain’s sinfulness and hardness of heart – Gen. 4:8. When God told him his punishment, he showed no repentance. All he was concerned about was the severity of the punishment.

 Cain had no respect for God. This is clear in all his reactions to God’s dealing with him. When God asked, "Where is your brother Abel?" He rudely replied, "I don't know," he replied. "Am I my brother's keeper?" Gen 4:9

Balaam and Job.. God rejected Balaam and approved Job for the following reasons:

Balaam did not love God but Job loved God.

Balaam’s lack of love for God was evidenced by his flagrant disobedience of God’s expressed order and will - Num 22:5, 12-22. Even in the peak of his suffering, Job was not guilty of disobedience of a single commandment of God Job said, ‘Though he slay me, yet will I trust in him.’ Job 13:15.

Balaam’s lack of love for God was evidenced by his covetousness (2 Peter 2:15-16) - love of worldly riches, honor and glory. Those who love God cannot love the world and those who love the world cannot love God (1 John 2:15). Job proved that he loved God more than worldly riches. When the devil struck and destroyed everything he had, Job said, ‘… the LORD gave, and the LORD hath taken away; blessed be the name of the LORD.’ Job 1:21. A servant of God who loved riches would have forsaken God straightaway.

 Balaam had no fear of God. A person who fears God will not allow himself to be persuaded to act against the will of God. A person who fears God will not risk incurring the wrath of God because of worldly riches and honor. Exodus 1:17, 21. Job showed he feared the Lord. The Bible testified, ‘In all this Job sinned not, nor charged God foolishly.’ Job 1:22.

Gehazi and Elisha. God rejected Gehazi, with the result that he was unable to step into Elisha’s shoe. God approved Elisha, enabling him to take the place of Elijah, with the double portion of the anointing in which Elijah operated. The reasons are:

Gehazi did not love God but Elisha loved God.

Gehazi’s lack of love for God was proved by the fact that he was more interested in the things of the world than in the things of God. He was quite aware of the great things the Lord was doing through His servant Elisha (2 Kings 8:4-5). And he was quite aware of the seriousness of the spiritual battle going on at the time, which did not justify diversion of the attention, by love of worldly riches, of those who are involved in the battle (2 Kings 5:26). But he would rather have worldly riches than heavenly anointing to accomplish his own part of the big task before the people of God. Profanity is a big proof of lack of love for God. Elisha would have nothing but the heavenly anointing. He desired nothing more than that the great work of God continued through him and that God be glorified in his life (2 kings 2:1-9).

Gehazi’s lack of love was proved by his rebellion against the decision of the man of God (2 Kings 5:20). He disobeyed the word of God that warns, ‘deceive not with thy lips’  Prov 24:28; ‘Ye shall not steal, neither deal falsely, neither lie one to another.’ Lev 19:11. The Bible didn’t relate a single case of disobedience of God’s word by Elisha or of an act of rebellion against Elijah, his master. And we know the Bible did not gloss over or cover up the sin and disobedience of any Bible character.

Gehazi was guilty of covetousness (2 Kings 5:20-24). Elisha was not interested in worldly riches and glory (2 Kings 5:25-27). He had access to the king and the Commanding Officer of the Israelites army, the two greatest men in Israel (2 Kings 4:13). If he had cared, he could become rich through his access to these two greatest men in Israel, who would just be too willing to fulfill the desires of the respected and feared prophet of God. But he chose to remain financially poor: he possessed no worthy property and has no fixed abode.

Judas and Peter. Acts 1:17-18; Matt 16:18-19. God rejected Judas and accepted Peter for the following reasons:

Judas did not love God but Peter loved God.

Judas’ lack of love was proved by the fact that he sided with the devil in his heart against Jesus - John 6:70-71. Peter proved he loved the Lord by standing firmly with the Lord since the time he was called to follow the good Lord. Even when he slipped in time of temptation, he quickly repented and got back in fellowship with the Lord he loved. John 21:17.

Judas’ lack of love was proved by his disobedience of a series of Jesus’ instructions, which would have led to life and honor for him if he had complied with. For example, he heard Jesus warning, “beware of covetousness: for a man's life consisteth not in the abundance of the things which he possesseth.” Luke 12:15. But he continued in his love of riches until it destroyed him (John 12:4-6). Nowhere in the Bible are we informed that Peter disobeyed the Lord, even once.

Judas’ lack of love for God was made clear by his love of money (John 12:4-6; Luke 22:3-6). Peter was approved of God because he did not allow love of riches to destroy his relationship with God - Acts 8:18-23. Though he had no money, he had a great divine anointing that showed God chose him.

Judas had no fear of God. But Peter feared the Lord. See how Judas behaved when Jesus rebuked him gently about his greed-motivated statement in Matt 26:8-16. The actual disciple who voiced these words was Judas, according to John 12:4-5. Only a person who did not fear God would react to such a fatherly advice like he did. The words Jesus spoke to Judas could not even qualify for a rebuke when you compare it with the harsh and brusque words the Lord spoke to Peter in Matt 16:23. Yet, Peter never took offence. He accepted the rough, stinging rebuke meekly because he loved and feared the Lord.