Summary of the New Testament:

Jesus Christ's life (from the virgin birth to His ministry, crucifixion, and resurrection) is the basis for the four Gospels -- the books of Matthew, Mark, Luke, and John. Jesus taught to love others as much as yourself and to love God as the one and only God. Jesus performed many miracles and healings, described the Kingdom of Heaven, and told people how to live as God wished them to live. Jesus' many story-illustrations were used to direct the people with things familiar to them. Jesus selected twelve disciples (since there were 12 "tribes" of Israel) to help Him and to spread the Word of God. Conflict with religious leaders (Pharisees and Sadducees) led to His crucifixion (death on the cross) after it was approved by Roman leaders (At the time of Jesus, Rome ruled the Jewish people, who longed for freedom.). Jesus Christ's death/sacrifice led to the:

New Covenant (contract) of God with all people (Jews and Gentiles [non-Jews])
(1) Written in their minds and hearts
(2) All who believe on Him are forgiven by Jesus Christ's sacrifice (by His blood)
to take away their sins.
Refer to:

• Jeremiah 31:33 (Old Testament reference)
• Matthew 26:28
• Mark 14:24
• Luke 22:20
• Romans 8:3
• Philippians 3:9
• Hebrews 8:10
• Hebrews 9:15
• Hebrews 10:9-10

which is further described by
John 3:16-- (from King James' Version)

"For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him should not perish, but have everlasting life."

The requirements for Christians: are given in 1 John 3:23
"And this is His command: to believe in the name of His Son Jesus Christ, and to love one another..."

After Christ's death and resurrection, Paul became converted to Christianity and extended the teachings to the Gentiles (Greeks, Romans, and other non-Jews), accounting for the early, rapid growth of Christianity in spite of great persecution of the believers. Jesus' death and resurrection and His expected return at the "last days" were told by Paul. Life after death was described by Paul (1 Corinthians 15:35-58), with a new, non-earthly body. The Revelation and other writings address the "last days" with Christians given life in heaven and others given to "the Lake of Fire" (hell).