General Christian View
Christians are mostly against euthanasia. The arguments are usually based on the beliefs that life is given by God and that human beings are made in the image of God.
Life is a gift from God. All life is God-given. Birth and death are part of the life processes which God has created, so we should respect them. Therefore no human being has the authority to take the life of any innocent person, even if that person wants to die
Human beings are valuable because they are made in God’s image. Human life possesses an intrinsic dignity and value because it is created by God in his own image for the distinctive destiny of sharing in God’s own life. Saying that God created humankind in his own image doesn’t mean that people actually look like God, but that people have a unique capacity for rational existence that enables them to see what is good and to want what is good. As people develop these abilities they live a life that is as close as possible to God’s life of love. This is a good thing, and life should be preserved so that people can go on doing this.
To propose euthanasia for an individual is to judge that the current life of that individual is not worthwhile. Such a judgement is incompatible with recognising the worth and dignity of the person to be killed. Therefore arguments based on the quality of life are completely irrelevant. Nor should anyone ask for euthanasia for themselves because no-one has the right to value anyone, even themselves, as worthless.
Position of Catholic Church
Nothing and no one can in any way permit the killing of an innocent human being, whether a fetus or an embryo, an infant or an adult, an old person, or one suffering from an incurable disease, or a person who is dying. Furthermore, no one is permitted to ask for this act of killing, either for himself or herself or for another person entrusted to his or her care, nor can he or she consent to it, either explicitly or implicitly, nor can any authority legitimately recommend or permit such an action. For it is a question of the violation of the divine law, an offense against the dignity of the human person, a crime against life, and an attack on humanity.
It may happen that, by reason of prolonged and barely tolerable pain, for deeply personal or other reasons, people may be led to believe that they can legitimately ask for death or obtain it for others. Although in these cases the guilt of the individual may be reduced or completely absent, nevertheless the error of judgment into which the conscience falls, perhaps in good faith, does not change the nature of this act of killing, which will always be in itself something to be rejected. The pleas of gravely ill people who sometimes ask for death are not to be understood as implying a true desire for euthanasia; in fact, it is almost always a case of an anguished plea for help and love. What a sick person needs, besides medical care, is love, the human and supernatural warmth with which the sick person can and ought to be surrounded by all those close to him or her, parents and children, doctors and nurses.
Position of Protestant Denominations
A number of Protestant denominations have issued statements on euthanasia and physician assisted suicide. Conservative faith groups tend to be most vocal in their opposition. Liberal denominations tend to be more in favor of individual choice.
Anglican: Rowan Williams, the Anglican Archbishop of Canterbury, has stated that although ‘There is a very strong compassionate case’ for physician-assisted dying, the Anglican Church remains opposed to the practice.Some Episcopalians believe it is morally wrong to take human life with medication to relieve suffering caused by incurable illness. Others approve of assisted dying in rare cases.
Lutheran: As a church we affirm that deliberately destroying life created in the image of God is contrary to our Christian conscience. While this affirmation is clear, we also recognize that responsible health care professionals struggle to choose the lesser evil in ambiguous borderline situations — for example, when pain becomes so unmanageable that life is indistinguishable from torture.
Baptist: Assisted dying violates the sanctity of human life.
Methodist: Methodists generally accept the individual’s freedom of conscience to determine the means and timing of death. Some regional conferences have endorsed the legalization of physician assisted dying.‘Euthanasia’ or ‘mercy-killing’ of a patient by a physician or by anyone else, including the patient himself (suicide) is murder.
Presbyterian Church in America:
United Church of Christ: The Church affirms individual freedom and responsibility. It has not asserted that hastened dying is the Christian position, but the right to choose is a legitimate Christian decision.Pro-choice statements have been made by the United Church of Christ, and the Methodist Church on the US West coast. The Episcopalian, Methodist, and Presbyterian are amongst the most liberal, allowing at least individual decision making in cases of active euthanasia.
Mainline and Liberal Christian denominations:
Position of Judaism
Euthanasia, physician-assisted suicide, and all other types of suicide are almost unanimously condemned in Jewish thought, primarily because it is viewed as taking something (a human life) that belongs to God for “only He who gives life may take it away.” For Judaism, human life is, “created in the image of God.” Although life is considered to be God’s creation and good, human life is related to God in a special way: it is sacred. The sanctity of human life prescribes that, in any situation short of self-defense or martyrdom, human life must be treated as an end in itself. It may thus not be terminated or shortened because of considerations of the patient’s convenience or usefulness, or even sympathy with the suffering of the patient. Thus euthanasia may not be performed either in the interest of the patient or of anyone else.
Jewish law strongly condemns any act that shortens life and treats the killing of a person whom the doctors say will die in any event to be an act of murder. Positive euthanasia is thus ruled out. Even individual autonomy is secondary to the sanctity of human.
Position of Islam
Human life per se is a value to be respected unconditionally. The concept of a life not worth living does not exist in Islam. Justification of taking life to escape suffering is not acceptable in Islam. The Prophet Mohammad said: “Among the nations before you there was a man who got a wound and growing impatient with its pain, he took a knife and cut his hand with it and the blood did not stop until he died. Allah said, ‘My slave hurried to bring death upon himself so I have forbidden him to enter Paradise'” (Qur’an 4:29).
During one of the military campaigns one of the Muslims was killed and the companions of the prophet kept praising his gallantry and efficiency in fighting, but, to their surprise, the Prophet commented, “His lot is hell.” Upon inquiry, the companions found out that the man had been seriously injured so he supported the handle of his sword on the ground and plunged his chest onto its tip, committing suicide.
Patience and endurance are highly regarded and highly rewarded values in Islam. “Those who patiently persevere will truly receive a reward without measure” (Qur’an 39:10). “And bear in patience whatever ill maybe fall you: this, behold, is something to set one’s heart upon” (Qur’an 31:17). When means of preventing or alleviating pain fall short, this spiritual dimension can be very effectively called upon to support the patient who believes that accepting and standing unavoidable pain will be to his/her credit in the hereafter, the real and enduring life.
 “Declaration on Euthanasia”, The Sacred Congregation for the Doctrine of the Faith, May 5, 1980 http://www.usccb.org/prolife/tdocs/euthanasia.shtml (accessed March 14, 2011)
 “Religion and Spirituality” The Death with Dignity National Center (DDNC), Oct. 13, 2009 http://euthanasia.procon.org/view.answers.php?questionID=000154 (accessed March 14, 2011)