You and we all should learn what a monster is and what a good person is to begin with.
Perhaps your going by what your parents taught you, and you take that to be the Truth.
In fact Islamic teachings are the Truth. What do I mean by Islamic teachings?
First, the Qur'an (the Speach of Allah).
Second, the Sunnah the ways and teachings and approvals of the final Messenger Prophet Muhammad (Allah's Peace and Blessings be Upon Him). He (Allah's Peace and Blessings be Upon Him) was mentioned in the Torah and Gospel.
Third, the first two (The Qur'an and the Sunnah) with the understanding of Prophet Muhammad's (Allah's Peace and Blessings be Upon Him) companions (the Sahabah). Having the correct understanding of the Qur'an and the Sunnah. For example, there is no terrorism in Islam.
The Qur'an and the Sunnah with the understanding of the Sahabah is the Truth.
That's Orthodox, Sunni, Salafi Islam.
With the Orthodox Islamic Knowledge, we can differentiate between if a person is a monster or a good person.
I'm just trying to benefit y'all.