Because it is the unique nature of God to have the willingness, and the power, to forgive the sin of anyone who is genuinely sorry.
It is the very nature of God to forgive if the sinner is truly sorry (mercy is His very nature). Jesus died a horrible death to pay the price for our sins…a price has to be paid by someone. God, His Father, gave Jesus the power and authority to forgive sins.
Guilt and shame are powerful feelings. Some people suicide to be rid of the shame in their heart. Others do not care one iota. Jesus knows just how we feel and He is not mocked by lies and denial…but it is his pleasure to forgive our sins when we are truly sorry.
For an beautiful example of that power read Luke Chapter 23 verses 32 to 43 where Jesus forgives a convicted criminal and tells him that: “Today you will be with me in paradise.” Not half bad…crucified criminal today…in paradise tonight. The criminal was truly sorry. That’s the Jesus way!