Scientology is a very difficult religion to summarize in just a few paragraphs, let alone in a few pages. It was founded in 1953 by fiction author L. Ron Hubbard, just four years after he made the statement, "I'd like to start a religion. That's where the money is," to Lloyd Eshbach; quoted by Eshbach in Over My Shoulder. That's where he found wealth, also--Hubbard became a multi-millionaire. An easier question to ask would be, "What are the similarities between Christianity and Scientology?" The answer to that would be, "There are no similarities."
Scientology teaches that mankind is an immortal being (called a Thetan) not originally from this planet that is trapped by matter, energy, space, and time (MEST). Salvation for a Scientologist comes through a process called 'auditing,' whereby 'engrams' (basically, memories of past pain and unconsciousness that create energy blockage) are removed. Auditing is a very lengthy process and can cost hundreds of thousands of dollars. When all engrams are finally removed, the Thetan can once again control MEST instead of being controlled by it. Until salvation, each Thetan is constantly reincarnated.
Scientology is a very expensive religion to associate with. Every aspect of Scientology has some sort of fee associated with it. This is why Scientology's "pews" are filled only with the wealthy. It is also a very strict religion, and very punitive against those who would try to leave behind its teachings and membership. Its "scriptures" are limited solely to the writings and teachings of L. Ron Hubbard.
Scientology is, without a doubt, a cult: Its teachings are taken from science fiction and eastern mythologies; It promotes man as the ultimate power in the universe--he just hasn't realized it yet; Salvation comes through an extremely expensive process of mind games; and it categorically denies the existence of the God of the Bible, Heaven, and Hell. To a Scientologist, Jesus Christ was just another nice guy who unfortunately was wrongfully put to death, and whose story ends at that death.
Though Scientologists will claim that Scientology is compatible with Christianity, the Bible counters each and every point of belief they hold to: God is the sovereign and only creator of the universe (Genesis 1:1); Mankind was created by God (Genesis 1:27); the only salvation available to man is by grace through faith in the finished work of Jesus Christ (Philippians 2:8); salvation is a free gift that mankind can do nothing to earn (Ephesians 2:8-9); and Jesus Christ is alive and well, and is seated at the right hand of God the Father even now (Acts 2:33; Ephesians 1:20; Hebrews 1:3), awaiting the time when He will gather His children to Himself to reside with Him for eternity in Heaven. Everybody else will be cast into a very real Hell, separated from God (Revelation 20:15).
Scientology differs from Biblical Christianity on every important doctrine. Some of the most important differences are summarized below.
God: Scientology believes that there are multiple gods and that some gods are above other gods. Biblical Christianity, on the other hand, recognizes the One and Only True God who revealed Himself to us in the Bible and through Jesus Christ. Those that believe in Him cannot believe the false concept of God as taught in Scientology.
Jesus Christ: Like almost all other cults, Scientology denies the deity of Christ. Instead of having a biblical view of who Christ is and what He did, they assign to Him the characteristics of some sort of lesser God who has obtained a sort of legendary status over the years. On the other hand, the Bible clearly teaches that Jesus was God in the flesh and through His incarnation He could act as a sacrifice for our sins. It is through Christ’s death and resurrection that we can have the hope of eternal life with God.
Sin: Scientology believes in the inherent goodness of man and that “It is despicable and utterly beneath contempt to tell a man he must repent, that he is evil.” On the other hand, the Bible teaches that man is a sinner and the only hope for him is that he repent of his sins and acknowledge Christ as his Lord and Savior.
Salvation: Scientology believes in reincarnation and that personal salvation in one's lifetime is freedom from the cycle of birth and death associated with reincarnation. They believe that religious practice of all faiths is the universal way to wisdom, understanding, and salvation. On the other hand, the Bible teaches that there is only one way of salvation and that is through Jesus Christ. Jesus Himself said, “I am the way, the truth, and the life, no man comes to the Father except through me.” John 14:6.
When one looks at the teaching of Scientology in comparison with the Bible, he will see that the two have little if anything in common. Scientology will only lead you away from God and eternal life, and the Bible will lead you to God and eternal life. There is nothing to gain by associating with scientology and everything to lose.