Why does Karna refuse to join the Pandavas?

He never revealed his identity to the Pandavas inorder to emotionally weaken them or take any undue advantage to attain the throne or win the war. He was a man of self respect and as Kunti herself never revealed it to Pandavas so he too never did it.

What did Karna ask Krishna?

Karna always knew that the Pandavas would win the war of Kurukshetra. Lord Krishna asked Karna how he knew that the Pandavas would win the war, to which he replied, “Kurukshetra is a sacrificial field.

Does Krishna hate Karna?

Krishna never hated Karna. If he would have hated him, then he would have never went to speak to him to stop the war. He knows that Karna went in wrong path only due to the time beings and not by his nature. He always wanted Karna to be with him & his brothers.

Why Karna was not accepted?

During the Swayamvara of Draupadi Karna isn’t allowed to participate . It’s because he is of low caste than the other princes and members. Dronacharya doesn’t accept Eklavya as a pupil because he was the teacher of only the royal princes and not of any Nishada. Parshurama doesn’t accept any Kshatriya as his disciple .

Why did Karna fail to defeat Arjuna in the Mahabharata?

It was simply because of lack of skill. During the final battle, the only thing Arjuna did was kill Karna’s support and he did not run anything significant against him, although he counteracted some of his weapons. For more information see my answer: War between Karna and Arjuna – Mahabharata

Why did Lord Krishna want Arjuna to fight in the war?

Had Lord Krishna used weapon in the war, the war would have won by his merits. He want Arjuna to fight, because it was his battle. Lord Krishna wanted to prove a point. The battle was won by Arjuna alone, with Krishna’s divine assistance. He only wished to give moral support.

Why Krishna didn’t take part in the Mahabaratha battle?

This is an incident described in the Mahabaratha. Your answer doesn’t explain why Krishna didn’t take part in the battle. The answer as I know is that Krishna was willing to support Arjuna and Balrama was willing to support Duryodhana. but the brothers don’t want to fight themselves for others.

Should Karna thank Pandavas for giving a fair fight?

Karna & all other warriors who were cheated (by Krishna) actually should thank PAndavas for giving majorly a fair fight in general. Because the premises of the MahAbhArata war itself was on deceit.