Although De Niro has famously portrayed a number of overtly Catholic characters on screen, and he apparently has publicly indicated that he considers himself Catholic, there is no indication that he has ever lived as a practicing Catholic.
From: Andy Dougan, Untouchable: A Biography of Robert De Niro, Thunder's Mouth Press: New York (1996), page 5:
...Robert De Niro [Senior, i.e., Robert De Niro Snr, the father of the actor named Robert De Niro]... was born in 1922 in Syracuse in upper New York State to an Irish mother and Italian father. He grew up in a predominantly Irish neighborhood.Actor Robert De Niro's mother was named Virgina Admiral. She was a painter who had lived in the trendy Greenwich and SoHo neighborhoods of New York City, and had been educated partially at a very liberal, politically activist Berkeley University in California. As a student, she studied Communism, was part of a circle of actively Socialist friends, was interestedin poetry, went to political demonstrations, handed out leaflets, and received a BA degree in English literature (Dougan, pages 3-5). Robert De Niro's father (Robert De Niro Senior) was a painter whose themes included strongly Catholic themes, including the crucifixion. From: Dougan, page 6:
One of [Robert De Niro Senior's] friends described his involvement with art as a matter of life and death. His determination to create art in its purest form drove him to paint over work again and again in a quest for, if not perfection, then at least satisfaction. In 1958 the influential New York magazine ARTnews carried an article on De Niro with the intention of showing the artist at work. The work in question was a crucifixion, and De Niro's progress was tracked for a little more than two years.Dougan, page 6:
'. . . but due to his restive dissatisfaction with each start,' recalls the catalogue from the retrospective exhibition held in 1995, two years after his death, 'his painting and repainting and moving from canvas to canvas, the final essay is an account of frustration as each version of the subject underwent continual metamorphosis and ultimate rejection until at the end only one gouache survived.'
Admiral and De Niro [Virginia Admiral and Robert De Niro Senior] were an odd couple, he a volatile Irish-Italian, she an intellectual and fiercely independent. But oddly matched or not, they were a golden couple at Provincetown... They were among the best in the school, attracting attention in an atmosphere where painters either excelled or were ignored completely. Fellow students recall a tangible aura of potential greatness around this couple who had the respect of their teachers and their peers.Dougan, page 10:
But whatever aura of greatness surrounded them, it would not last long.
For some months [after the separation of future actor Robert De Niro Junior's parents separated, when he was two years old] the baby De Niro lived with his grandparents in Syracuse while custody arrangements were worked out. It was while he was with his grandparents that he was baptised a Roman Catholic, against his parents' wishes. His father had left the Church at the age of twelve and his mother, while raised a Presbyterian, was by now an atheist. The separation of the golden couple caused something of a scandal in their tightly knit artistic community, but it was made final with a divorce in 1953.Dougan, pages 172-173:
For Scorsese, who had once harboured serious thoughts of being a Catholic priest, there were compelling religious and theological reasons for making The Last Temptation of Christ. Despite their common background, De Niro does not share Scorsese's strong religious convictions. The Catholicism in his family comes from his grandmother but it was not strictly enforced, and there appears to be little room for formal religion in his life. But even without any overriding religious considerations, there was always friendship.Dougan, page 93:
'I was not interested in playing Christ. It's like playing Hamlet,' he explained. 'I just didn't want to do it. Marty and I talked about it. We do things with each other because we like to work together, but also for our separate reasons. I have mine as an actor, he has his as a director. That's the best way.
'Last Temptation was something I was never interested in doing. But I did tell him, "If you really have a problem, if you really want to do it, and you need me, I'll do it. If you're against the wall and have no other way, I'll do it as a friend."'
Scorsese appreciated the gesture, but he also points out that when it was made De Niro had had his head shaved for a prosthetic that was required in Once Upon a Time in America. Both me probably knew in their hearts that the world was not yet ready for a balding Christ... [Eventually] Willem Dafoe played Christ
America in the mid-seventies was at the heart of yet another debate on the place of the cinema as a guardian of the nation's morals. Taxi Driver [starring Robert De Niro] was seized by both sides. Those who argued for greater censorhip saw it as little more than an abomination, with the former seminarian Scorsese [who directed it] the nearest thing to the Antichrist in human form. Those who argued for greater liberalism hailed the film... as a masterpiece that proved what could be done when artists were allowed the freedom to create great work.Dougan, page 96:
So De Niro went unrewarded for one of the great performances in the American cinema [his performance in Taxi Driver, because the Academy Award went to Peter Finch, who died after having been nominated for his role in Network]. His [De Niro's] only consolation may have been that he could have been a two-time loser [but wasn't, because he had already won for The Godfather, Part II]. Another Oscar hopeful that year was [Mormon film director] Hal Ashby's Bound for Glory, a big-budget biopic of the folk singer Woody Guthrie. De Niro was one of several actors who turned down the role before it was eventually taken by David Carradine.Dougan, page 112:
In 1979 it was a two-horse race between The Deer Hunter and another Vietnam film, Coming Home. Hal Ashby's movie [Coming Home] starred Jane Fonda and Jon Voight and focused on the plight of the returning veterans. The Academy was split in much the same way as audiences had been split. Many felt that The Deer Hunter was far too controversial and played fast and loose with the truth; others felt that Coming Home presented an idealised picture of life for the returning veterans. [More on this topic.]Dougan, pages 155-156:
The climate in Hollywood at that time [late 1970s] was very different to the health-obsessed fitness culture that currently pervades in the movie capital of the world. Since about 1975, cocaine had been king in Hollywood... Hal Ashby, the acclaimed director of Shampoo and Coming Home, claimed that cocaine use was reaching epidemic proportions in Hollywood by that stage. He used it himself but says he stopped when it began to impair his judgement and made him snap at trusted friends.Actress Cathy Moriarty recounts the experience of being cast in Raging Bull, page 126:
Looking back on those early days, Cathy Moriarty is still stunned by the whole experience. One regret now is that she never quite appreciated what was happening to her at the time... 'He [Robert De Niro] was an absolute gentleman to me. He was lovely, he was very concerned and caring. You have to consider that at this stage I was only eighteen years old. Here I was, an Irish-Catholic girl being pitched into this situation with these three single Italian men. But Robert De Niro and Martin Scorsese were so exceptionally lovely to me and so concerned and so caring that I will always be grateful to them.'Dougan, pages 135-136:
Even the weight loss [after having put on pounds for his role as a boxer in Raging Bull] was factored into his next characterisation, in True Confessions, which he consciously started when he was about fifteen pounds above his regular fighting weight. He believed it would make his character look sleek and well fed. He and Robert Duvall play brothers who in 1948 become involved in a notorious Los Angeles murder. Duvall is the detective, De Niro plays a priest. His Monsignor Desmond Sellacy is a ruthless, upwardly mobile priest who has all but forsaken his vocation for the sake of influence and power. His main patron is the man who his brother Tom, played by Duvall, suspects of being heavily involved in the killing.Dougan, page 168:
Duvall's investigation leads to the end of both of their careers. But De Niro's monsignor, relegated to an obscure desert parish away from the bright lights of the Los Angeles social scene, is at least redeemed for having rediscovered his vocation.
Members of the Catholic media and the Catholic hierarchy praised De Niro for his characterisation. They pointed out that Monsignor Desmond Spellacy was the most convincing cleric seen on screen in years. Given that De Niro had used his still-fleshy features to convey the impression of a 'fat cat' priest who has grown comfortable by paying more attention to his secular rather than his religious duties, it may not have been quite as much of a compliment as they thought.
...While he was playing the priest on screen his off-screen sinning was continuing. He as still seeing Helena Lisandrello, who by this time claimed that she had become pregnant by accident, and that De Niro was the father.
'It happened at Chateau Marmont,' she told Cindy Adams of the New York Post... 'I didn't have my diaphragm,' she continued. 'But I knew he didn't love me so I didn't tell him. I aborted. He never knew.'
...September 1992 the newspapers announced that De Niro had become a father again by 'his mistress, the black singer Helena Springs'. (Springs was Lisandrello's professional name.) De Niro was of course still married at the time, although separated from Diahnne Abbott... According to newspaper reports... De Niro was delighted and had showered gifts on the child... The newspaper reports went on to say that De Niro and his mistress had named their new baby daughter Nina Nadeja. Ten year later, in the midst of a savagely fought paternity suit, Lisandrello would remember the circumstances somewhat different when she spoke to Cindy Adams.Dougan, pages 180-181:
'This time I told Bobby [Robet De Niro],' she said, referring to the pregnancy she had hidden from him the previous year... 'He said, "You can't have that [expletive] baby. What are your plans?" I said, "I will not have an abortion." He turned hateful and that began his ten years of cruelty to me. He was drinking and he never allowed me to be happy for one moment. He'd say, "Your job is to [expletive] me between planes, bitch, not to get pregnant." It was mental abuse.'
The Mission is the story of how Spain and Portugal carved up Latin America in the eighteenth century. It is also the story of how the original spiritual intention of converting the heathen was subverted to commercial ends when the Jesuit missions in the rainforest were destroyed to allow commerce to take over. Jeremy Irons plays Gabriel, an idealistic Jesuit who has founded a Utopian community among the Indians of the rain forest. De Niro plays Mendoza, a former slaver and mercenary who has come to the mission to atone for killing his brother in a duel. When it becomes apparent that the mission cannot survive, these two men take different approaches to the problem. Gabriel puts his faith in prayer and cannot believe that his new oppressors will attack the mission; Mendoza reverts to his old ways and forms some of the Indians into a guerilla group, this time fighting for the Lord. Neither of them is proved right. Both men are killed, the mission is overrun, and the Indians are massacred.
Casting De Niro was a bold step. He was quintessentially a modern, urban actor and this was a period costume piece featuring the sort of robes he could not see himself in when Scorsese discussed The Last Temptation of Christ. The suggestion was first made by Roland Joffe, who felt De Niro would be ideal for the role... De Niro, who had already told Joffe that he was willing to reduce his fee to play the role, graciously said he appreciated the [tight budget] situation and guaranteed that he would not be responsible for delaying shooting in any way.
[More about De Niro's role in The Mission, which is regarded by many as one of the greatest Catholic-themed feature films ever made.]