How can one respond to someone who believes that the details of creed related to God's attributes are unnecessary for the soundness of religion, and that the focus should be on acts of worship and ethics, especially when this comes from a strong friendship and cooperation in Islamic activities at the university?

If the truth is clear to you and you predominantly believe there is no deception on their part, then there is no objection to cooperating with them and refraining from discussing matters of disagreement. This is to achieve the greater good and confront the greater danger. The Ummah today is in dire need of mutual support and cooperation to overcome its crises, not division and argumentation over existing differences. This does not mean compromising the creed of Ahl al-Sunnah wal-Jama'ah; rather, it is a call to unite efforts towards action and construction, emulating the conduct of earlier scholars who called for cooperation on what was agreed upon and tolerance on what differed.

The common people are not required to delve into complex theological disputes. Rather, they should suffice with the established statements from the text and consensus, and be prevented from delving into details that could lead to division and discord. Differences regarding the Qur'an should lead to abandoning debate if it results in discord and fitnah, not to polemical disputation aimed at demonstrating the truth.

It must be borne in mind that whoever is ignorant of something from the religion is excused until the proof becomes clear to them. And whoever knows the details of what the Messenger brought is more perfect in faith and loyalty to Allah.

The summary is to gather with students who are keen on their religion in da'wah and student activities to support Islam, and to avoid argumentation over doctrinal details if it leads to division. Otherwise, there is no harm in dialogue if it is with wisdom and good admonition, and in an atmosphere of love.