The Congregation for the Doctrine of the Faith responds in the negative to the possibility of imparting a blessing to unions of same-sex couples, noting that it “does not imply a judgment on persons” involved.
These are the motivations at the basis of the negative response. The first regards the truth and value of blessings, which are ‘sacramentals’, liturgical actions of the Church which require that what is being blessed be “objectively and positively ordered to receive and express grace, according to the designs of God inscribed in creation”. Relationships, even if stable, “that involve sexual activity outside of marriage” – meaning, outside “the indissoluble union of a man and a woman”, open to the transmission of life – do not respond to the “designs of God”, even if “positive elements” are present in those relationships. This consideration not only concerns same-sex couples, but also unions that involve the sexual activity outside of matrimony. Another reason for the negative response is the risk that the blessing of same-sex unions may be mistakenly associated with that of the Sacrament of Matrimony.
Read full presentation by the Press Office of the Holy See, Holy See: The Church cannot bless same-sex unions – Vatican News
See full text of the Responsum ad dubium published by the CDF.
See also full text of the Commentary to the Responsum ad dubium issued by the Press Office of the Holy See.