He [Jesus Christ] is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world.

1 John 2:2-6 (ESV, Holy Bible)
2 He [Jesus Christ] is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world.
3 We know that we have come to know him if we keep his commands.
4 Whoever says, “I know him,” but does not do what he commands is a liar, and the truth is not in that person.
5 But if anyone obeys his word, love for God is truly made complete in them. This is how we know we are in him:
6 Whoever claims to live in him must live as Jesus did.