A German Catholic priest has admitted 280 counts of sexual abuse involving three boys in the past decade, saying he did not think he was doing harm.
After being banned by his diocese from making further contact with the boy, he abused two brothers, aged nine and 13.
Thousands of Germans have left the Church over revelations of abuse.
About 180,000 renounced their Catholicism in 2010, up 40% from the previous year, the German broadcaster Deutsche Welle reports.
Pope Benedict XVI, a German by birth, briefly met victims of sexual abuse by priests when he visited his native land in September, expressing "deep compassion and regret" at their suffering.
The priest on trial in Braunschweig faces a minimum prison sentence of between six and six and a half years.
He was arrested during the summer, after the mother of his earlier victim reported him to the authorities.
She acted after her son, now aged 17, revealed to her the abuse he had undergone for two years.
The priest, who covered his face with a ring binder as he went into court on Thursday, said that while working in Braunschweig in 2004, he had begun a close relationship with the widow.
When Fr Andreas was moved to Salzgitter, her son often spent weekends with him, and the two would go off on short trips.
He would give the boy presents such as a camera and a mobile phone.
Abuse would often occur three times a weekend.
The priest said it had not been his intention to get close to the boy sexually, and that it had never occurred to him that he was doing harm.
When the mother began to suspect her son's relations with the priest were inappropriately close, she approached the diocese of Hildesheim, the priest's employer, which forbade further contact with the boy.
The abuse of the two brothers then began under similar circumstances, the court heard.
After contact with these victims was also forbidden, the priest approached his first victim again, writing him a letter.
It was then that the truth about the abuse emerged.
"It was never my impression that the children did not consent," the priest was quoted as saying at the trial.
When asked in court if he was a paedophile, he replied, according to local newspaper Braunschweiger Zeitung: "It would be wrong to say No but to say Yes would also fall short of the truth."
When a prosecutor asked him in court if he thought a "father would do this to his children", he was silent.
About 2,800 pornographic images were found on the priest's computer, including several of his victims.
Correspondents say members of the public who were in the courtroom watched the trial with faces rigid from shock.
They included parishioners from St Joseph's Church in Salzgitter, where Fr Andreas had once been a respected priest, according to Germany's Spiegel magazine.