That title was bestowed by the Romans beginning before 700BC, so it clearly pre-dates Christianity and the Catholic church.
Incomplete list of Pontifices Maximi
753 BC to 712 BC - Duties and power of office (even if perhaps not the title) held by the Kings of Rome
712 BC - Numa Marcius
...
509 BC - Papirius
...
449 BC - Quintus Furius
431 BC - Cornelius Cossus
420 BC - Spurius Minucius[35][36]
390 BC - Follius Flaccinator
...
332 BC - Cornelius Callissa
304 BC - Cornelius Scipio Barbatus, possibly Lucius Cornelius Scipio Barbatus
...
254 BC - Tiberius Coruncanius
243 BC - Lucius Caecilius Metellus (d. 221 BC), resigned or removed from office circa 237 BC.
237 BC - Lucius Cornelius Lentulus Caudinus (d. ca 213 BC)
212 BC - Publius Licinius Crassus Dives (d. 183 BC),
183 BC - Gaius Servilius Geminus (d. 180 BC), possibly Gaius Servilius C.f. Geminus
180 BC - Marcus Aemilius Lepidus (d. 152 BC)
152 BC - Vacant
150 BC - Publius Cornelius Scipio Nasica Corculum (d. 141 BC)
141 BC - Publius Cornelius Scipio Nasica Serapio (d. 132 BC Pergamum, Asia Minor)
132 BC - Publius Licinius Crassus Dives Mucianus (killed in battle 131 BC, Asia Minor)
130 BC - Publius Mucius Scaevola (d. 115 BC or 113 BC)
115 BC - Lucius Caecilius Metellus Dalmaticus,
103 BC - Gnaeus Domitius Ahenobarbus (d. 88 BC)
89 BC - Quintus Mucius Scaevola Pontifex (murdered 82 BC in the Temple of Vesta)
81 BC - Quintus Caecilius Metellus Pius (d. ca 63 BC)
63 BC - Gaius Julius Caesar (d. 44 BC)
44 BC - Marcus Aemilius Lepidus, triumvir (d. 13 BC),
6 March 12 BC - Augustus
12 BC to AD 376 - Held by the Emperors
From some indeterminate later date to present, the title "Pontifex Maximus" is applied to the Popes.
http://en.wikipedia.org/wiki/Pontifex_Maximus
