My father says we must hate Buddhist and Hinduists because they are mushrikin. I don't really hate them or see them as enemy. Is that normal?
There is no reason to hate them. Hatred often causes you to be blind to the good qualities in the person you hate and to only see the bad qualities in them.
We must instead treat them the way the Quran teaches us to treat people, and the way the Prophet ﷺ treated his pagan extended family and neighbors. The Prophet ﷺ did not gather his following by preaching hatred and intolerance toward others. He did it by preaching recognizing God’s Oneness and the importance of connecting with Him, and by preaching good manners and patience toward the insults and attacks of the pagans against the Muslims.
Here is an anecdote about the Prophet ﷺ and his treatment of his arch-enemy Ibn Ubayy in Al-Madinah:
The Prophet’s leniency toward this hypocrite continued until Ibn Ubayy died of natural causes. The Prophet accepted to have his (own) garment used as Ibn Ubayy’s burial shroud upon Ibn Ubayy’s son’s request.
The Quran says that God would not forgive the like of Ibn Ubayy even if the Prophet asked for forgiveness for them seventy times, so the Prophet said he would ask for his forgiveness more than seventy times. He accepted to pray at his funeral, after which verse 9:84 of the Quran was revealed which prohibited him from praying at the funerals of proven hypocrites. (From my book A Beautiful Path to God).
The Prophet ﷺ, instead of finding excuses to hate this man who spent most of his time plotting against the Muslims, continued to find excuses for him, and honored him after death by letting his own garment be used as his burial shroud.
Prophet Ibrahim was a similar person as is recorded in the Quran:
74. When Abraham's fear subsided, and the good news had reached him, he started pleading with Us concerning the people of Lot.
75. Abraham was gentle, kind, penitent.
76. “O Abraham, refrain from this. The command of your Lord has come; they have incurred an irreversible punishment.” (The Quran, verses 11:74-76)
The angels had arrived to tell Prophet Ibrahim that they were about to destroy Sodom and Gomorrah, which were inhabited by a people who were homosexual rapists and robbers. Instead of rejoicing at the news of the destruction of these people, Prophet Ibrahim argues with the angels on their behalf, wanting to block the punishment.
And the Quran does not blame Prophet Ibrahim for trying to block the punishment, instead praises him for it in verse 75 above.
The Prophet Muhammad ﷺ and his ancestor Prophet Ibrahim are role models in kindness and tolerance toward others, including toward non-believers. It is the example of these two men that we must follow above all others.
If individual Buddhists or Hindus, or groups of them, commit a crime against Muslims then they should be dealt with as the case requires, the way the Prophet ﷺ dealt with the Jews, hypocrites and pagans who plotted to destroy the Muslims. But there is nothing in the Quran and the Prophet’s life ﷺ to teach us to have a blanket hatred toward people who mean us no harm just because they are not Muslim.
As for those who have not fought against you for your religion, nor expelled you from your homes, God does not prohibit you from dealing with them kindly and equitably. God loves the equitable. (The Quran, verse 60:8)