In support of the fact that religion purposely and knowingly would prefer and allow a person to suffer horrible slow deaths to terminal illness rather than a humane death by euthanasia:
According to Christian teaching, however, suffering, especially suffering during the last moments of life, has a special place in God's saving plan; it is in fact a sharing in Christ's passion and a union with the redeeming sacrifice which He offered in obedience to the Father's will.
The Varican's Declaration on Euthanasia, found here