To what extent is the hadith "No one loves Ali except a believer, and no one hates him except a hypocrite" authentic, and how can this be reconciled with the Kharijites' hatred for Ali and the love of the Batinite sects for him?

Faith has degrees, increasing and decreasing, and similarly, disbelief and hypocrisy. Love for Ali (may Allah be pleased with him) indicates faith, and hatred for him indicates hypocrisy, because he supported the religion, was an early convert to Islam, and held a special status with the Messenger of Allah (peace and blessings be upon him). Therefore, whoever loves him for these reasons, it is a sign of the soundness of their faith, and whoever hates him for these reasons, it is a sign of hypocrisy. This applies to all the Companions: loving them is faith, and hating them is hypocrisy.