How should Christians test a religious tradition?

He condemns using a dedication to God as a reason to withhold support from one’s parents. That practice nullified the command to honor father and mother, so Jesus says God’s command must not be displaced by a human tradition.

You identify the concrete harm and the commandment it displaced, rather than making the passage a blanket rejection of tradition.

He says every religious tradition and every authority outside the written Bible is invalid.

That is broader than the example. Jesus condemns a tradition used to evade God’s command; the passage does not address every kind of tradition or authority.

Yes. Paul tells that community to hold to what they were taught “by word” or by his letter. Oral apostolic instruction and written instruction both carried authority for them; the verse alone does not establish how authority continued after the apostles.

You recognize the force of Paul’s oral instruction while keeping the passage’s audience and time in view.

No. Paul only means the written letter, because scripture is always the only authority.

Paul explicitly distinguishes teaching received by word from teaching received by letter. A later argument is needed to explain how apostolic authority was preserved.

Scripture is the final authority that binds the conscience; church teachers and creeds can still guide interpretation, but they must yield when they conflict with Scripture. Mark 7 supports the warning about overriding God’s command, while the broader claim that the canon is closed needs its own argument.

You state the Protestant position as a final-standard claim, not as a denial that tradition or teachers have any role.

Protestants believe church history and teachers have no value at all.

That is a caricature. This Protestant defense allows subordinate teachers and creeds, while reserving final authority for Scripture.

I would first identify the exact instruction and who issued it, then check the scripture or official teaching that supports it and what authority is claimed. Doctrine and Covenants 1:38 affirms that the Lord speaks through servants, while 121:41–42 limits righteous authority to persuasion, patience, gentleness, and love. A title alone neither proves divine authorization nor proves contradiction.

You test a concrete teaching by its source and claimed authority, and apply an LDS scriptural limit without using the leader’s title as a shortcut.

If the instruction came from a leader, it is automatically God’s will and cannot be questioned.

That conclusion does not follow from authority language alone. The specific claim, its source, and scriptural limits on authority still need examination.