Which emperor initiated the first empire-wide persecution of Christians? (r. 249-251 AD)

The story behind the answer

Decius is correct because in 250 AD he issued an empire-wide edict requiring all inhabitants to perform a public sacrifice to the Roman gods and obtain a certificate (libellus) proving compliance. Christians who refused were punished, leading to arrests, martyrdoms (e.g., Pope Fabian), and many “lapsed” believers—sparking later church debates about penance. This was the first systematic, empire-wide policy targeting Christians.

By contrast, Nero’s notorious persecution after the Great Fire of 64 AD was largely confined to Rome, not the whole empire; Claudius mainly expelled some Jews from Rome; and Caracalla is known for granting citizenship to most free inhabitants in 212