Conservative bishops have taken the lead at the Pope's Synod on the Family in Rome, drawing a firm line against any attempts to soften rules that exclude divorced and remarried Catholics from communion and ban all artificial contraception.

In his opening address to Synod, the influential traditionalist Cardinal Péter Erdő made clear his view that the role of the synod should be to change nothing but strengthen and reinforce existing teachings. 

He said: "It is not the shipwreck of the first marriage but the living together in the second relationship that impedes access to the eucharist. God offers sinners pardon, but demands conversion."

He repeated his oft-stated view on the indissolubility of marriage being central to the teaching of Christ, the gospels and St Paul.

Cardinal Erdő said marriage and family life was a vocation and "the true meaning of our being made male and female". The family was the place where people learn the meaning of the "common good" through experience. Mercy and revealed truth could not be in "opposition" to each other.

He went on to repeat an argument of St John Paul II, that if a man and woman after divorce are in a second marriage that they should stay in for the sake of children or their common life, they must have a sexless marriage "as one of mutual help and friendship". This reflects the truth of marriage as taught by Christ, he argued. Irregular relationships could be positive but this did not mean they were "good".

The Cardinal, Rapporteur-General for the 270 bishops at the synod, making him a powerful and significant figure whose words will carry enormous weight, also attacked any possibility of a shift on homosexuality. "There is no basis for comparing or making analogies, even remotely, between homosexual unions and God's plan for matrimony and the family."

And he restated the Church's ban on artificial contraception. "This truth seems to have a special relevance today when there are so many technical possibilities for separating procreation from conjugal love."

Commentator John Allen, associate editor of Crux, described the address as the opening blow in the coming battle between conservatives and liberals at the three-week synod. "He seemed determined to close a series of doors that many people believed the last synod had left open — beginning with the controversial proposal of German Cardinal Walter Kasper to allow divorced and civilly remarried Catholics to return to Communion," he wrote.

Cardinal Erdő himself said in a press conference afterwards that he was responding to letters he had received from the faithful all over the world after the 2014 Synod on the Family and the resulting working document for this synod, which had seemed to open the door to possible change.

The well-informed blogs One Peter Five and Rorate Caeli speculated on three possible outcomes to the 2015 synod and said the straightforward affirmation of doctrine that conservatives want is not ultimately probable. The latter reported: "The third outcome is the most probable one -- the theoretical affirmation of doctrine, combined with the formal legalisation or official toleration of practice that will severely undermine it."