Since the Church states that it is possibles for those who are non-catholics through no fault of their own to go to heaven, can I request a mass be said for the soul of a deceased relative who was born and remained a Methodist?
Yes. The Church lovingly calls us to pray for all those who have died in need of purification (Catholic or non-Catholic). And because the Church does not propose to know if any particular soul is damned, we are not to judge, but to pray. We are to offer prayers, “above all the Eucharistic sacrifice, so that, thus purified, they may attain the beatific vision of God.” (*Catechism of the Catholic Church * 1039).