Soteriology

Soteriology (; ' "salvation" from σωτήρ ' "savior, preserver" and λόγος "" "study" or "word") is the study of religious doctrines of salvation. Salvation theory occupies a place of special significance in many religions. In the academic field of religious studies, soteriology is understood by scholars as representing a key theme in a number of different religions and is often studied in a comparative context; that is, comparing various ideas about what salvation is and how it is obtained.
Buddhism.
Buddhism is devoted primarily to liberation from suffering by breaking free of "samsara", the cycle of compulsory rebirth, by attaining "nirvana". Many types of Buddhism, Theravada, Mahayana and Vajrayana (or Tantric), emphasize an individual's meditation and subsequent liberation from "samsara", which is to become enlightened.
However, the Pure Land traditions of Mahayana Buddhism generally focus on the saving nature of the Celestial Buddha Amitābha. In Buddhist eschatology, it is believed that we are currently living in the Latter Day of the Law, a period of 10,000 years where the corrupt nature of the people means the teachings of the Buddha are not listened to. Before this era, the "bodhisattva" Amitābha made 48 vows, including the vow to accept all sentient beings that called to him, to allow them to take refuge in his Pure land and to teach them the pure "dharma". It is therefore considered ineffective to trust in personal meditational and even monastic practices, but to only trust in the primal vow of Amitābha.
Christianity.
In Christianity, salvation, also called "deliverance" or "redemption", is the saving of human beings from sin and its consequences. Variant views on salvation are among the main lines dividing the various Christian denominations, being a point of disagreement between Eastern Orthodoxy, Roman Catholicism and Protestantism, as well as within Protestantism, notably in the Calvinist–Arminian debate. These lines include conflicting definitions of depravity, predestination, atonement, and most pointedly, justification. Christian soteriology ranges from exclusive salvation to universal reconciliation concepts.
While some of the differences are as widespread as Christianity itself, the overwhelming majority agrees that salvation is made possible by the life, crucifixion, death, and resurrection of Jesus.
Hinduism.
Soteriology is discussed in Hinduism through its concept of "moksha". “In India,” wrote Mircea Eliade, “metaphysical knowledge always has a soteriological purpose.” Moksha refers to freedom from saṃsāra, the cycle of death and rebirth.
Islam.
Muslims believe that everyone is responsible for their own actions. So even though Muslims believe that Adam and Hawwa (Eve), the parents of humanity, committed a sin by eating from the forbidden tree and thus disobeying God, they believe that humankind is not responsible for such an action. They believe that God (Allah) is fair and just and one should request forgiveness from him to avoid being punished for not doing what God asked of them and for listening to Satan. Muslims believe that they, as well as everyone else, are vulnerable to making mistakes and thus they need to seek repentance repeatedly at all times. 
Muhammad said "By Allah, I seek the forgiveness of Allah and I turn to Him in repentance more than seventy times each day." (Narrated by al-Bukhaari, no. 6307) God wants his servants to repent and forgives them, he rejoices over it, as Muhammad said: "When a person repents, Allah rejoices more than one of you who found his camel after he lost it in the desert." (Agreed upon. Narrated by al-Bukhaari, no. 6309) Islamic tradition has generally held that it is relatively straightforward to enter "Jannah" (Paradise). In the Quran, God says:
"If you avoid the great sins you have been forbidden, We shall wipe out your minor misdeeds and let you through the entrance of honor [Paradise]."
Jainism.
In Jainism, the soteriological concept is "moksha", but it is explained differently than the similar term found in Hinduism. Moksha is a blissful state of existence of a soul, completely free from the karmic bondage, free from saṃsāra, the cycle of birth and death.
Judaism.
In contemporary Judaism, redemption (Hebrew "ge'ulah") is God's redeeming the people of Israel from their various exiles. This includes the final redemption from the present exile. Judaism holds that adherents do not need personal salvation, as Christians believe. Jews do not believe in original sin. Instead, they place a high value on individual morality as defined in the law of God—embodied in what Jews know as the Torah or The Law, given to Moses by God on Mount Sinai, the summary of which is comprised in the Ten Commandments. The Jewish sage Hillel the Elder states that The Law can be further compressed in just one line, popularly known as the Golden Rule: "That which is hateful to you, do not do unto your fellow".
In Judaism, salvation is closely related to the idea of redemption, saving from the states or circumstances that destroy the value of human existence. God, as the universal spirit and creator of the world, is the source of all salvation for humanity, provided an individual honours God by observing his precepts. So redemption or salvation depends on the individual. Judaism stresses that salvation cannot be obtained through anyone else or by just invoking a deity or believing in any outside power or influence.
Some passages in Jewish religious texts assert that no afterlife exists, even for the good and just, with the Book of Ecclesiastes telling the faithful: "The dead know nothing. They have no reward and even the memory of them is lost." For many centuries, rabbis and Jewish laypeople have often wrestled with such passages.
Mystery religions.
In the mystery religions, salvation was less worldly and communal, and more a mystical belief concerned with the continued survival of the individual soul after death. Some savior gods associated with this theme are dying-and-rising gods, often associated with the seasonal cycle, such as Osiris, Tammus, Adonis, and Dionysus. A complex of soteriological beliefs was also a feature of the cult of Cybele and Attis.
The similarity of themes and archetypes to religions found in antiquity to later Christianity has been pointed out by many authors, including the Fathers of the early Christian church. One view is that early Christianity borrowed these myths and motifs from contemporary Hellenistic mystery religions, which possessed ideas such as life-death-rebirth deities and sexual relations between gods and human beings. While Christ myth theory is not accepted by mainstream historians, proponents attempt to establish causal connections to the cults of Mithras, Dionysus, and Osiris among others.
Sikhism.
Sikhism advocates the pursuit of salvation through disciplined, personal meditation on the name and message of God, meant to bring one into union with God. But a person's state of mind has to be detached from this world, with the understanding that this world is a temporary abode and their soul has to remain untouched by pain, pleasure, greed, emotional attachment, praise, slander and above all, egotistical pride. Thus their thoughts and deeds become "nirmal" or pure, and they merge with God or attain "union with God", just as a drop of water falling from the skies merges with the ocean.
Other religions.
Shinto and Tenrikyo similarly emphasize working for a good life by cultivating virtue or virtuous behavior.
In an age which still saw salvation as primarily collective - based on the religion of the family, clan, or state - rather than the emerging province of the individual (as popularized by Buddhism and the mystery religions such as Mithraism), Hellenistic ruler cults from about 300 BCE sometimes promoted the revering of a king as the savior of his people. Prominent examples included Ptolemy I Soter of Egypt and the Seleucids Antiochus I Soter and Demetrius I Soter. In the Egyptian context, the deification of a ruler built on traditional pharaonic religious ideas.