I completely understand how reading stories like this in the bible can be confusing but this is not what Christianity is all about. The most accurate representation of Christianity was given when Christ was on earth. he gave 2 laws in which Christians are meant to live by:

"Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. 38This is the first and great commandment. 39And the second is like unto it, Thou shalt love thy neighbour as thyself."(Matthew 22:37-39)

These laws can be extrapolated to this:

"3Thou shalt have no other gods before me.

4Thou shalt not make unto thee any graven image, or any likeness of any thing that is in heaven above, or that is in the earth beneath, or that is in the water under the earth: 5thou shalt not bow down thyself to them, nor serve them: for I the LORD thy God am a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate me; 6and shewing mercy unto thousands of them that love me, and keep my commandments.

7Thou shalt not take the name of the LORD thy God in vain; for the LORD will not hold him guiltless that taketh his name in vain.

8Remember the sabbath day, to keep it holy. 9Six days shalt thou labour, and do all thy work: 10but the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: 11for in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.

12Honour thy father and thy mother: that thy days may be long upon the land which the LORD thy God giveth thee.

13Thou shalt not kill.

14Thou shalt not commit adultery.

15Thou shalt not steal.

16Thou shalt not bear false witness against thy neighbour.

17Thou shalt not covet thy neighbour's house, thou shalt not covet thy neighbour's wife, nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing that is thy neighbour's." (Exodus 20)

You might recognise these as the 10 Commandments. The first 4 refers to God and the last 6 refer to mankind. Although this doesn’t give all the answers of the bible a complete explanation, Hopefully, this gives you an understanding of what Christianity is all about and the main theme of the bible, because as Jesus said “On these two commandments hang all the law and the prophets” (Matthew 22:40)