Billy Vunipola has been warned about his future conduct by Saracens after his online support for the Australia full-back Israel Folau, who has been served with a termination of contract notice for repeatedly using his social media accounts to tell sinners to repent.

Folau, who has two days to respond to Rugby Australia’s ruling that he committed a “high-level breach of the professional players’ code of conduct” which merited his contract being ripped up, defined sins as “adultery, fornication, uncleanness, lasciviousness, idolatry, witchcraft, hatred, variance, emulations, wrath, seditions, heresies, envying, murders, drunkenness and revellings”, quoting from the bible.

Vunipola, the England and Saracens No 8, liked Folau’s post, saying “there comes a point where you insult what I grew up believing in that you just say enough is enough. What he [Folau]is saying is not that he doesn’t like or love those people. He’s saying how we live our lives needs to be closer to how God intended them to be.”

Vunipola received support from some fellow players and criticism from others. He was booed when he came off the bench for Saracens at Bristol on Saturday and has since met officials from the Premiership champions. “We recognise the complexity of different belief systems and understand Billy’s intention was to express the word of God rather than cause offence,” said the club in a statement on Monday.

“However, he made a serious error of judgment in publicly sharing his opinion, which is inconsistent with the values of the club and contravenes his contractual obligations. The player has been formally warned about his future conduct.”

Vunipola said his intention was to express his belief in the word of God. “It was never to cause suffering. I can see that my post has hurt people. This is deeply personal and does not represent the views of my team. My Christian faith has sustained me through the ups and many downs of my life.”

Later this week Vunipola will meet the RFU, which will remind him of his responsibilities as a leading sporting figure and of the consequences should he post something similar again.

If Folau, who was warned last year about the homophobic nature of his posts, does not contest the notice of termination, he will be sacked by the Waratahs and Australia. He has the right to take the matter to a tribunal but, whatever the outcome, the Wallabies’ head coach, Michael Cheika, said he would not be picking the 30-year old again.

New Zealand will also be without a full-back in the World Cup with Damian McKenzie ruled out until next year after suffering knee ligament damage. The Harlequins and Australia second-row James Horwill will retire at the end of the season at the age of 33, while the Wales outside-half Gareth Anscombe will join the Ospreys next season from Cardiff Blues.