In 1 John 2:1,
John wrote (most likely to the churches near Ephesus -or so says the footnote in my Bible)
"My little children, these things I write to you, so that you may not sin."
"And if anyone sins..." (because we unfortunately do)
"we have an Advocate with the Father," (an advocate pleads our case and secures our pardon)
And we happen to have the very best One who could possibly advocate for us:
"Jesus Christ the righteous." I love that!
(because of course, another human sinner couldn't secure us a pardon)
How did He?
By becoming the sinless sacrifice required by our sinfulness.
"And He Himself is the propitiation for our sins," (that churchy word means that Jesus Himself became the sacrifice)
And I love this part:
"and not for our (sins) only but also for the WHOLE WORLD." (emphasis mine!) : )