Monolatry or monolatrism (Greek: ????? (monos) = single, and ??????? (latreia) = worship) is belief in the existence of many gods but with the consistent worship of only one deity. The term "monolatry" was perhaps first used by Julius Wellhausen.
Monolatry is distinguished from monotheism, which asserts the existence of only one god, and henotheism, a religious system in which the believer worships one god without denying that others may worship different gods with equal validity.
The ancient Egyptian Pharaoh Akhenaten initially introduced Atenism in Year 5 of his reign (1348/1346 BCE), during the 18th dynasty. He raised Aten, once a relatively obscure Egyptian Solar deity representing the disk of the Sun, to the status of Supreme God in the Egyptian pantheon.
The fifth year of Amenhotep IV's reign is believed to mark the beginning of his construction of a new capital, Akhetaten (Horizon of the Aten), at the site known today as Amarna. Amenhotep IV officially changed his name to Akhenaten (Agreeable to Aten) as evidence of his new worship. In addition to constructing a new capital in honor of Aten, Akhenaten also oversaw the construction of some of the most massive temple complexes in ancient Egypt, including one at Karnak and one at Thebes, close to the old temple of Amun.
In his ninth year of rule (1344/1342 BCE), Akhenaten declared a more radical version of his new religion, declaring Aten not merely the supreme god of the Egyptian pantheon but the only God of Egypt, with himself as the sole intermediary between the Aten and the Egyptian people. Key features of Atenism included a ban on idols and other images of the Aten, with the exception of a rayed solar disc in which the rays (commonly depicted ending in hands) appear to represent the unseen spirit of Aten. Aten was addressed by Akhenaten in prayers, such as the Great Hymn to the Aten.
The details of Atenist theology are still unclear. The exclusion of all but one god and the prohibition of idols was a radical departure from Egyptian tradition, but most scholars see Akhenaten as a practitioner of monolatry rather than monotheism, as he did not actively deny the existence of other gods; he simply refrained from worshiping any but Aten. It is known that Atenism did not solely attribute divinity to the Aten. Akhenaten continued the cult of the Pharaoh, proclaiming himself the son of Aten and encouraging the Egyptian people to worship him. The Egyptian people were to worship Akhenaten; only Akhenaten and Nefertiti could worship Aten directly.
Under Akhenaten's successors, Egypt reverted to its traditional religion, and Akhenaten himself came to be reviled as a heretic.
Some historians have argued that ancient Israel originally practiced a form of monolatry or henotheism. Both Frank E. Eakin, Jr. and John J. Scullion believe Moses was a monolatrist rather than a monotheist, and John Day suggests that angels are what became of the other gods once monotheism took over Israel.
"In the ancient Near East the existence of divine beings was universally accepted without questions.... The question was not whether there is only one elohim, but whether there is any elohim like Yahweh."
Some scholars claim the Torah (Pentateuch) shows evidence of monolatrism in some passages. The argument is normally based on references to other gods, such as the "gods of the Egyptians" in the Book of Exodus (Exodus 12:12). The Egyptians are also attributed powers that suggest the existence of their gods; in Exodus 7:11-13, after Aaron transforms his staff into a snake, Pharaoh's sorcerers do likewise. In the ancient Near East, the existence of magic was generally believed though the Israelites viewed it as being malign in origin and were forbidden from it. With regard to miracle and prophecy, the Bible commands the Israelites to not follow false prophets (those who compromise the law) and not to refrain from putting them to death. The miracles of false prophets are, like those of the Egyptian sorcerers, regarded by the Israelites as a divine test to see if the Israelites "love the LORD [their] God with all [their] heart and with all [their] soul".
The Ten Commandments have been interpreted by some as evidence that the Israelites originally practiced monolatrism.Exodus 20:3 reads "Thou shalt have no other gods before me," (Hebrew:?? ??????? ????? ????? ??????), and they argue that the addition of "before me" at the end of the commandment indicates that not only other gods may exist but that they may be respected and worshiped so long as less than Yahweh.
There is evidence that the Israelite people as a whole did not strictly adhere to monotheism before the Babylonian exile in the 6th century BCE. Much of this evidence comes from the Bible itself, which records that many Israelites chose to worship foreign gods and idols rather than Yahweh.
During the 8th century BCE, the monotheistic worship of Yahweh in Israel was in competition with many other cults, described by the Yahwist faction collectively as Baals. The oldest books of the Hebrew Bible reflect this competition, as in the books of Hosea and Nahum, whose authors lament the "apostasy" of the people of Israel and threaten them with the wrath of God if they do not give up their polytheistic cults.
On the other hand, medieval scholars often interpreted ancient texts to argue that the ancient Israelites were monotheistic. The Shema Yisrael is often cited as proof that the Israelites practiced monotheism. It was recognized by Rashi in his 11th century commentary to Deuteronomy 6:4 that the declaration of the Shema accepts belief in one god as being only a part of Jewish faith at the time of Moses but would eventually be accepted by all humanity.
God, the Cause of all, is one. This does not mean one as in one of a pair, nor one like a species (which encompasses many individuals), nor one as in an object that is made up of many elements, nor as a single simple object that is infinitely divisible. Rather, God is a unity unlike any other possible unity. This is referred to in the Torah (Deuteronomy 6:4): "Hear Israel, the Lord is our God, the Lord is one."
Paul the Apostle, in his First Epistle to the Corinthians, writes that "we know that an idol is nothing" and "that there is none other God but one" (1 Corinthians 8:4-6). He argues in verse 5 that "for though there be that are called gods, whether in heaven or in earth", "but to us there is but one God". Paul distinguishes between gods that have no authority or have a lesser authority, "as there be gods many, and lords many," and the one God who has universal authority, "one God, the Father, of whom are all things" and "one Lord, Jesus Christ, of whom are all things". Some translators of verse 5, put the words "gods" and "lords" in quotes to indicate that they are gods or lords only so-called.
In his Second Epistle to the Corinthians, Paul refers to "the god of this world" (2 Corinthians 4:4), which is generally interpreted as referring to Satan or the material things put before God, such as money, rather than acknowledging any separate deity from God.
The Church of Jesus Christ of Latter-day Saints (LDS Church) teaches that God the Father, Jesus Christ and the Holy Ghost are three distinct beings belonging to one Godhead: "All three are united in their thoughts, actions, and purpose, with each having a fullness of knowledge, truth, and power." Latter-day Saints further believe that prayer should be directed to only God the Father in the name of Jesus Christ.
Jeffrey R. Holland has stated: "We believe these three divine persons constituting a single Godhead are united in purpose, in manner, in testimony, in mission. We believe Them to be filled with the same godly sense of mercy and love, justice and grace, patience, forgiveness, and redemption. I think it is accurate to say we believe They are one in every significant and eternal aspect imaginable except believing Them to be three persons combined in one substance."
Latter-day Saints interpret Jesus' prayer in , "Holy Father, keep through thine own name those whom thou hast given me, that they may be one, as we are" to refer to the characteristics, attributes and purpose that the Son shares with the Father in the hope that people can someday share in those as well. In Mormonism, being one with God means gaining immortality, perfection, eternal life, and the highest level in his kingdom. As D. Todd Christofferson states, "we may become one with God" as Jesus did.
Joseph Smith taught that humans can become joint-heirs with Christ and thereby inherit from God all that Christ inherits if they are proven worthy by following the laws and ordinances of the gospel. This process of exaltation means that humans can literally become gods through the atonement; thus, "god" is a term for an inheritor of the highest kingdom of God. That allows for the existence of many gods in the future, but only one as ruler over life in this universe.
To the extent that monolatry is not considered monotheism, the classification of Mormonism as monolatrous is strongly disputed among Latter-day Saints. Bruce R. McConkie stated that "true saints are monotheists." 
9 And He said unto me: 'Go in, and see the wicked abominations that they do here.' 10 So I went in and saw; and behold every detestable form of creeping things and beasts, and all the idols of the house of Israel, portrayed upon the wall round about. 11 And there stood before them seventy men of the elders of the house of Israel, and in the midst of them stood Jaazaniah the son of Shaphan, every man with his censer in his hand; and a thick cloud of incense went up. 12 Then said He unto me: 'Son of man, hast thou seen what the elders of the house of Israel do in the dark, every man in his chambers of imagery? for they say: The LORD seeth us not, the LORD hath forsaken the land.' 13 He said also unto me: 'Thou shalt again see yet greater abominations which they do.' 14 Then He brought me to the door of the gate of the LORD'S house which was toward the north; and, behold, there sat the women weeping for Tammuz. 15 Then said He unto me: 'Hast thou seen this, O son of man? thou shalt again see yet greater abominations than these.' 16 And He brought me into the inner court of the LORD'S house, and, behold, at the door of the temple of the LORD, between the porch and the altar, were about five and twenty men, with their backs toward the temple of the LORD, and their faces toward the east; and they worshipped the sun toward the east.-- Ezekiel 8 9-16, JPS translation
But where are thy gods that thou hast made thee? Let them arise, if they can save thee in the time of thy trouble; for according to the number of thy cities are thy gods, O Judah.-- Jeremiah 2 28, JPS translation