Why do Arabs and Jews not live in harmony in a country called Palestine, while the Bible does not mention a country called Israel, and both are descendants of Abraham and are brothers?

The Jews violated the monotheistic religion of Abraham and committed polytheism, so there is no brotherhood between a monotheistic believer and a polytheistic disbeliever. Indeed, Abraham disavowed those who worshipped other than Allah.

It is impossible to coexist harmoniously with usurping and aggressive Jews, who are known for treachery, betrayal, and corruption. They cannot be trusted due to their failure to uphold covenants. Islam is supreme and nothing is supreme over it. Among the conditions for the People of the Book to reside in Muslim lands is their adherence to the conditions of dhimma (protected status) and not openly displaying their disbelief.

Muslims and Jews are two religiously and ideologically disparate and hostile entities, and they cannot come together unless one submits to the other.

The current state of weakness among Muslims does not mean this situation will persist, for the Prophet (ﷺ) informed us that Muslims will fight the Jews and defeat them.