The social networking sites – often associated with postings of idle gossip and baby photos – could be used as "portals of truth and faith" in an increasingly secular age, the pontiff said in his 2013 World Communications Day message.
"Unless the good news is made known also in the digital world, it may be absent in the experience of many people," the 85-year-old pope said in the a letter published on the Vatican's website.
The Holy See has become an increasingly prolific user of social media since it launched its "new evangelisation" of the developed world, where some congregations have fallen in the wake of growing secularisation and damage to the church's reputation from a series of sex abuse scandals.
The pope himself reaches around 2.5-million followers through eight Twitter accounts, including one in Latin.
Belying his traditionalist reputation, the pope praised connections made online which he said could blossom into true friendships. Online life was not purely a virtual world but "increasingly becoming part of the very fabric of society", he said.
A practical Catholic tool
Social networks were also a practical tool that Catholics could use to organise prayer events, the pope suggested. But he called for reasoned debate and respectful dialogue with those with different beliefs, and cautioned against a tendency towards "heated and divisive voices" and "sensationalism".
The websites were creating a new "agora", he added, referring to the gathering spaces that were the centres of public life in ancient Greek cities.
The speech coincided with the launch of The Pope App, a downloadable program that streams live footage of the pontiff's speaking events and Vatican news onto smartphones.
Pope Benedict's embrace of new media responds to the church's concern that it is invisible on the internet.
The Vatican commissioned a study of internet use and religion prior to the pope's Twitter debut, which found the majority of US Catholics surveyed were unaware of any significant church presence online. – Reuters