How can a middle school student be convinced of the error in the idea of interfaith tolerance and acceptance of the other, using arguments suitable for their intellectual level?

The term "interfaith tolerance" contains both truth and falsehood. Some have used it as a means to mix truth with falsehood by making Islamic ethics a tool to affirm a disbeliever in their disbelief. The Islamic way of dealing with people of different religions is based on two virtues:

First, sincerity. Islam calls for acknowledging the disbelief of those who contradict the religion of Islam and inviting them to Islam, because true mercy lies in striving for their salvation from hellfire, not in affirming them in their disbelief, as the prophets used to do.

The second virtue is justice and beneficence. Islam does not command forcing non-Muslims to embrace Islam, nor does it command oppressing them if they refuse. Rather, it calls for beneficence in inviting them with wisdom and good admonition, and for justice in dealing with them if they insist on their disbelief.