Q- At the same time, if that is the case, then why is it that some Christians and Jews will also be in Paradise according to the Quran?

A- The Age
In the name of Allah, the Beneficent, the Merciful.

[103.1] I swear by the time,
[103.2] Most surely man is in loss,
[103.3] Except those who believe and do good, and enjoin on each other truth, and enjoin on each other patience.