MADRID, Aug 20, 2011 (AFP) - Pope Benedict XVI warned against "false gods" as he celebrated mass in Madrid's cathedral Saturday, embarking on a final weekend of dazzling Catholic festivities, hit by repeated protests.
Tens of thousands of young pilgrims, many waving national flags and wearing orange floppy hats made for August 16-21 World Youth Day celebrations, cheered his arrival at Madrid's Almudena Cathedral.
Wearing a white cassock, scarlet cape and white skullcap, and with a gold pectoral cross hanging from his neck, the 84-year-old pontiff descended from the popemobile.
The leader of the world's 1.2 billion Roman Catholics Episcopal sprinkled holy water at the entrance and donned a white, gold-embroidered mitre before walking down the 120-metre aisle of the 19th century cathedral to celebrate mass for young people preparing to join the priesthood.
"Do not be intimidated by surroundings that would exclude God and in which power, wealth and pleasure are frequently the main critiera ruling people's lives," the pope warned the seminarians.
"You may be shunned along with others who propose higher goals or who unmask the false gods before whom many now bow down."
Earlier in the morning, the pope heard confession from four young pilgrims -- two women and two men -- in Madrid's city-centre Retiro park.
Media access was restricted to keep the confessional private, but television helicopter cameras showed the pope's party at the centre of a line of 200 temporary confessionals set up in the park.
Priests sit on one side of the open-sided structures, separated by a plank of wood and a grille from the sinner kneeling on a built-in stool. A small cover shields both from the August sun.
The pope will hold a "Prayer Vigil" in the evening at an airbase southwest of the capital, where the pilgrims will spend the night under the stars on an esplanade the size of 48 football pitches.
He celebrates mass there on Sunday morning at a white altar almost 200 metres (660 feet) long in front of a wave-shaped stage and under a giant parasol "tree", made of interwoven golden rods.
The sheer scale of the celebrations in Madrid has sparked angry demonstrations, however, over the expense at a time of economic hardship, with unemployment for under-25s running at more than 45 percent.
Thousands of protesters marched in central Madrid late Friday to protest the expense and to decry police crackdowns on earlier demonstrations.
"This is not the pope youth!" and "No to police violence!", the crowd chanted, waving their hands in the air.
Scores of police prevented the activists from marching into the city's central Puerta del Sol square, where clashes took place on both Wednesday and Thursday nights.
Baton-wielding anti-riot police in Madrid late Thursday dispersed about 150 protesters from the square. And on Wednesday 11 people were reported lightly injured when police dispersed a protest.
Protesters - including some priests -- are fuming over the official 50.5-million-euro ($73-million) price tag, excluding the cost of police and security, of the Catholic youth celebrations.
But organisers of the festivities say most of the cost will be covered by a registration fee from the pilgrims, and the celebration will be a massive tourist boost for Spain.