Bishop Tartaglia (Letters, May 14) argues that religious faith is well-equipped to shed light on scientific and moral matters surrounding the use of embryos. But which faith?

In the Jewish Chronicle in March, Jewish leaders from across the religious spectrum united in their support of the Embryology Bill, with rabbis from all shades of Judaism, from Liberal to Orthodox and Reform, dis-agreeing vehemently with the position put forward by Cardinal O'Brien.

Baroness Rabbi Julia Neuberger, who was on the scrutiny committee for the bill, said that Jews had a different view on when life begins to the Catholic view, while from a Reform perspective, Rabbi Dr Jonathan Romain of Maidenhead synagogue said the creation of human-animal hybrid embryos for medical research was not to be condemned as "Frankenstein science", but to be welcomed as a life-saving development "that uses our God-given skills in the noblest of causes. It is irresponsible to hold back the progress that could benefit so many lives".

No doubt the bishop disagrees with the Jewish perspective. It is clear, however, that an appeal to religious faith to resolve moral questions merely complicates the problem, rather than presenting a definitive solution. Whose "faith" position should we trust - the Catholic or the Jewish?

Alistair McBay, National Secular Society, 5 Atholl Crescent, Edinburgh.

Bishop Tartaglia suggests that a greater focus on the moral status of the embryo is needed. Perhaps he could answer a few simple questions from his position as a faith leader: Why is it wrong to create, experiment on and destroy embryos if this will not hurt them and the alternative is that they never exist at all?

Given that most embryos "die" in the womb, do their souls go to heaven?

If there were a scientific breakthrough and a cure for Parkinson's was found that relied on embryo research, would the bishop change his position?

Faith positions cannot be described as wise unless they are backed up by reasons; the real debate is between those who offer arguments in support of their views and those who do not.

Dr David Shaw, Lecturer in Ethics, University of Glasgow.