When spiritual deception takes root, the blame does not rest solely on the one telling the lies. Responsibility for sin and its resulting punishment falls equally on the misleading leader and the individual who approaches him with improper intentions. Both parties will carry the heavy burden of their actions, bearing full responsibility for the consequences [מצודת ציון, ביאור שטיינזלץ]. Their guilt is absolutely identical, ensuring that the penalty they receive will be exactly the same [מצודת ציון, רד״ק, מצודת דוד].
The individuals involved in this mutual deception share a deeply flawed dynamic. The inquirer is someone who outwardly appears to seek guidance from God or a true prophet, yet secretly harbors idol worship and evil thoughts in his heart [מצודת דוד, רד״ק, ביאור שטיינזלץ]. Another perspective suggests this refers to a person who pretends to seek knowledge, but actually refuses to absorb or apply any moral lessons [רש״י, רד״ק]. Regardless of the specific inner flaw, the inquirer cannot claim innocence by arguing that the prophet misled him, since he never should have sought out a false prophet to begin with [מלבי״ם]. On the other side is the prophet himself, who may be a complete fraud speaking outright lies [מצודת דוד], or a leader who gives in to temptation and tells his audience inappropriate falsehoods [ביאור שטיינזלץ].
God issues this severe and equal punishment to completely uproot deception from the community. The ultimate goal is to ensure that the Israelites will no longer stray in their faith or defile themselves through the corrupting influence of false prophets [מלבי״ם].