I'm not sure where you're going with this, but please explain more. Do you mean that Matthew 5:48 "Be perfect, therefore, as your heavenly Father is perfect" does not agree with what I wrote above?
It doesn't disagree with what you wrote. What I'm looking at is the difference between a faith-based approach to salvation and a theologicial approach, particularly regarding the ideals of justice and perfection which are present in the sermon on the mount.
Every Christian probably finds the sermon on the mount beautiful and challenging, too. The blood of Christ washes away all the sins of all those who prove to be among God's elect. Christ's work here is perfect, is it not?
There's a symbolic aspect to the blood of the last supper, which is represented by wine:
For this is my blood of the new testament(diatheke), which is shed for many for the remission of sins.
But I say unto you, I will not drink henceforth of this fruit of the vine, until that day when I drink it new with you in my Father's kingdom.
Matthew 26:26-27
Diatheke means covenant. The're also symbolism relating to the practice and consent of the people of the covenant:
And he took the book of the covenant, and read in the audience of the people: and they said, All that YHWH hath said will we do, and be obedient.
And Moses took the blood, and sprinkled
it on the people, and said, Behold the blood of the covenant, which YHWH hath made with you concerning all these words.
Exodus 24:7-8
The law of the old covenant relates to the law of the new covenant:
Behold, the days come, saith YHWH, that I will make a new covenant with the house of Israel, and with the house of Judah:
Not according to the covenant that I made with their fathers in the day
that I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith YHWH:
But this
shall be the covenant that I will make with the house of Israel; After those days, saith YHWH, I will put my law in their inward parts, and write it in their hearts; and will be their Elohim, and they shall be my people.
Jeremiah 31:31-33
I am not greatly familiar with comparisons of Jonah's experience with the death and Resurrection of Jesus. Someone with greater learning than I will have to comment here.
Here's the text that relates the sign of Jonah to the crucifixion, for which the law is not relevant:
Matthew 12