1 John 1:9 ESV
If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
1 John 1:9 is one of the most loved and memorized verses of all time. We use it often and much yet I fear because of its over use we may gloss over its weight. Much like our desensitization of the cross as an actual capital punishment death chamber, also our understanding of sin and judgement has been desensitized.
Consider what had to be done for sin before the Cross, before Jesus for someone to be “cleansed from all unrighteousness.” A reading of the Old Covenant points to the redemption of the Lamb that was slain. We gloss over these verses but when you consider the sheer mass of animal sacrifices that went on during that time it is mind boggling. I used to visualize the priest in his white robe and ephod dazzling in the sun looking good in his Sunday School best. Realistically, however, they were covered in blood. Any butcher can tell you that animal killing is a messy business. The volume of animals sacrificed coupled with the continual throwing of the blood on the alter, I am certain the whole ordeal was a bloody splattered mess. Read the verses at the end to give you an idea of the masses of animals that were sacrificed. Don’t miss this: blood flowed, and it flowed heavily. This was no light matter.
So how, and why can a God who is righteous, a God who is just, be able to forgive us with the sacrifice of just ONE Man? That question alone is where we veer off course. The question should not be in light of the Man Jesus. That one Man was THE Lamb. He was the Lamb that was described over and over again in the Old Covenant. He was without blemish. Spotless. Perfect. Without sin… He. Was. GOD! God gave himself up as the heaviest thickest richest blood that would ever be or could ever be. It was His blood that was enough. His blood that could carry the weight of the sins of the world. Don’t miss it beloved! The weight of His blood should weigh on your heart every time you consider it. Your sin should weigh on your heart every time you consider it. He died and bled pure perfect righteous blood for you. He lived a life that was perfect. He lived a life you never could and died a death you deserved. All for you! It was the only way. Ponder it. Wonder at it. Glorify Him for it. Live for Him because He did something you could never accomplish and because of Him you are free. This verse should be memorized. It should be often flowing from your mouth. But consider the weight of it the next time you share it or meditate on it. It is quite a big deal. Praise God!
Here are some verses to give you some reference:
1 Chronicles 29:21 ESV
 And they offered sacrifices to the LORD, and on the next day offered burnt offerings to the LORD, 1,000 bulls, 1,000 rams, and 1,000 lambs, with their drink offerings, and sacrifices in abundance for all Israel.
2 Chronicles 29:21-22 ESV
 And they brought seven bulls, seven rams, seven lambs, and seven male goats for a sin offering for the kingdom and for the sanctuary and for Judah. And he commanded the priests, the sons of Aaron, to offer them on the altar of the LORD.  So they slaughtered the bulls, and the priests received the blood and threw it against the altar. And they slaughtered the rams, and their blood was thrown against the altar. And they slaughtered the lambs, and their blood was thrown against the altar.
2 Chronicles 35:7 ESV
 Then Josiah contributed to the lay people, as Passover offerings for all who were present, lambs and young goats from the flock to the number of 30,000, and 3,000 bulls; these were from the king’s possessions.