Question: "What is Christianity and what do Christians believe?"
Answer: 1 Corinthians 15:1-4 says, “Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain. For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; And that he was buried, and that he rose again the third day according to the scriptures.”
In a nutshell, that is the belief of Christianity. Christianity is unique among all other faiths, because Christianity is more about a relationship, rather than religious practice. Instead of adhering to a list of “dos and don’ts,” the goal of a Christian is to cultivate a close walk with God the Father. That relationship is made possible because of the work of Jesus Christ, and the ministry in the life of the Christian by the Holy Spirit.
Christians believe that the Bible is the inspired, inerrant Word of God, and that its teaching is the final authority (2 Timothy 3:16, 2 Peter 1:20-21). Christians believe in one God that exists in three persons, the Father, the Son (Jesus Christ), and the Holy Spirit.
Christians believe that mankind was created specifically to have a relationship with God, but that sin separates all men from God (Romans 5:12, Romans 3:23). Christianity teaches that Jesus Christ walked this earth, fully God, and yet fully man (Philippians 2:6-11), and died on the cross. Christians believe that after His death on the cross, Christ was buried, He rose again, and now lives at the right hand of the Father, making intercession for the believers forever (Hebrews 7:25). Christianity proclaims that Jesus’ death on the cross was sufficient to completely pay the sin debt owed by all men and this is what restores the broken relationship between God and man (Hebrews 9:11-14, Hebrews 10:10, Romans 6:23, Romans 5:8).
In order to be saved, one must simply place his faith entirely in the finished work of Christ on the cross. If someone believes that Christ died in his own place and paid the price of his own sins, and rose again, then that person is saved. There is nothing that anyone can do to earn salvation. Nobody can be “good enough” to please God on his or her own, because all of us are sinners (Isaiah 64:6-7, Isaiah 53:6). Secondly, there is nothing more to be done, because Christ has done all the work! When He was on the cross, Jesus said, “It is finished” (John 19:30).
Just as there is nothing one can do to earn salvation, once someone has placed his/her trust in the work of Christ on the cross, there is nothing anyone can do to lose his/her salvation either. Remember, the work was done and completed by Christ! Nothing about salvation is dependent upon the one who receives it! John 10:27-29 states “My sheep hear my voice, and I know them, and they follow me: And I give unto them eternal life; and they shall never perish, neither shall any [man] pluck them out of my hand. My Father, which gave [them] me, is greater than all; and no [man] is able to pluck [them] out of my Father's hand.”
Some may think, “This is great--once I am saved, I can do just as I please, and not lose my salvation!” But salvation is not about being free to do as one pleases. Salvation is becoming free from having to serve the old sin nature, and being free to pursue a right relationship with God. As long as believers live on this earth in their sinful bodies, there will be a constant struggle with giving in to sin. Living in sin hinders the relationship God seeks to have with mankind, and as long as one lives in sin as a believer, he will not enjoy the relationship God intended to have with him. However, Christians can have victory over the struggle with sin by studying and applying God’s Word (the Bible) in their lives, and being controlled by the Holy Spirit--that is, submitting to the Spirit’s influence and leading in everyday circumstances, and through the Spirit obeying God’s Word.
So, while many religious systems require that a person do certain things or not do certain things, Christianity is about having a relationship with God. Christianity is about believing that Christ died on the cross as payment for your own sin, and rose again. Your sin debt is paid and you can have fellowship with God. You can have victory over your sin nature and walk in fellowship and obedience with God. That is true biblical Christianity.