Unconditional impermissibility of suicide
The restrictive extreme position argues for the unconditional impermissibility of any form of suicide. Therefore, it is under any circumstances ethically impermissible to kill oneself for the purpose of a more self-determined and less painful dying. Furthermore, within this position there is a debate on the question of the ethical legitimacy of a wish to die.
In the history of philosophy, this position has sometimes been defended with reference to duties toward God (Thomas Aquinas) and duties toward ourselves (Immanuel Kant).
The argument from the "inviolability" and "sanctity" of life, which prohibits any curtailment of one's own life, is formulated by the churches in the context of the euthanasia debate in the following documents:
Franjo Cardinal Seper. (1980, May 5). Sacred Congregation for the Doctrine of the Faith: Declaration on Euthanasia. In Acta Apostolicae Sedis 72. https://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_19800505_euthanasia_en.html
John Paul II. (1995, March 25). Encyclical Letter Evangelium Vitae: To the bishops, priests and deacons, men and women religious, lay faithful and all people of good will on the value and inviolability of human life. Esp. sections 64-67. https://www.vatican.va/content/john-paul-ii/en/encyclicals/documents/hf_jp-ii_enc_25031995_evangelium-vitae.html
Kirchenamt der Evangelischen Kirche in Deutschland, & Sekretariat der Deutschen Bischofskonferenz (Hrsg.). (1996). Im Sterben: Umfangen vom Leben. Gemeinsames Wort zur Woche für das Leben 1996: "Leben bis zuletzt - Sterben als Teil des Lebens". Gemeinsame Texte Nr. 6. https://www.ekd.de/23653.htm
Kirchenamt der Evangelischen Kirche in Deutschland, & Sekretariat der Deutschen Bischofskonferenz (Hrsg.). (2011). Sterbebegleitung statt aktiver Sterbehilfe Eine Sammlung kirchlicher Texte. Gemeinsame Texte Nr. 17. www.ekd.de/ekd_de/ds_doc/sterbebegleitung_statt_aktiver_sterbehilfe_gt17_2011.pdf
See for this position in philosophy:
Aquin, T. v. (1953). Summa Theologica II–II, Frage 57–79, Recht und Gerechtigkeit (Die deutsche Thomas-Ausgabe, Bd. 18). Styria, Kerle.
Finnis, J. (1995). A Philosophical Case Against Euthanasia (pp. 23–35). Keown.
Kant, I. (1998). Groundwork of the Metaphysics of Morals (Cambridge Texts in the History of Philosophy, translated and edited by Mary Gregor with an introduction by Christine M. Korsgaard). Cambridge University Press.