However, the 76-year-old disgraced former head of the White Fathers from their Cypress Grove headquarters in Templeogue Dublin, still maintains his innocence.
In a statement issued through his solicitor Joe McVeigh outside Belfast's Laganside Courthouse on Thursday, the paedophile priest, also placed on the Sex Offenders' Register for life, claimed that his Co Throne trial in Omagh Crown Court was a "miscarriage of justice".
While he acknowledged and respected the jury who convicted him of the eleven charges of indecent assault against the three sisters when they were aged between seven and thirteen, Fr Lewis' solicitor said the priest intended to "fight to the last drop of his bloods to establish his innocence completely".
Mr McVeigh added that "very many people from all over the world have expressed their outrage at his conviction and that he took great comfort from knowing that he has their support".
During his six-week trial the court had heard that Father Lewis had also allegedly raped one of the girls in the White Fathers' Dublin headquarters, not once but twice.
She had been sent there by her parents to be counselled by Father Lewis because she was having an affair with a married policeman.
The priest also allegedly interfered with the girls' eldest sister in the White Fathers' seminary in Blacklion just across the border from her Co Fermanagh home where her sisters were being abused.
When sentencing him Judge Philip Babington said that while these alleged incidents could be considered as "background information," and made it clear that "this court does not take those alleged matters into account in this sentencing process".
Judge Babington, who also disqualified Father Lewis from working with children or vulnerable adults, said that the impact on his three victims had been immense and that one of them, in the words of one doctor, had been "chronically and deeply affected".
The judge added that it was "also clear that all found the trial deeply upsetting and stressful".
He said later that they had been "subjected to lengthy intrusive cross examination which at times was clearly embarrassing" during the trial although that questioning was "carried out thoroughly and professionally".
The court had heard that the abuse lasted for over a decade from August 1963 until September 1973.
During that time the judge said that Father Lewis was "encouraged" by the girls' parents to visit their home, although the visits were infrequent.
However the court had heard that he often visited at bedtime or on Saturday bath-night and that he had even managed to abuse one of the girls in front of her father, his actions hidden by a large kitchen table.
During the trial evidence from 21 character witnesses from Africa, Germany and Ireland about Father Lewis, an ordained priest since 1958, was given to the court.
Judge Babington said that there "is no doubt that he is held in high regard by persons in those countries and by ex-students and colleagues".
But the judge added: "However the very nature of these types of cases does mean that the offending behaviour usually takes place in private and well away from the eyes of colleagues, family and friends."
The judge said while he was taking that evidence into account, "in cases such as these that does not count to any great degree".
Judge Babington said there were a number of aggravating factors in the case including the fact his victims "were very, very young when they were abused," and that the abuse continued over a period of some ten years and that there had been and still is, "a significant impact on the injured parties as evidenced by the victim impact reports".
He also described the case as "a blatant and very serious breach of trust - all of the complainants were abused in their own home while under the same roof as their parents, with the exception of one of them who was on her own and in some ways this makes it even worse.
"He is also seen as a figure of authority."
In all Father Lewis was given sentences ranging from 15 to 18 months on each of the 11 charges.
While each of the sentences involving each victim were concurrent, they were made to run consecutive to each other, making a total of four years.