Isaiah 1  Four times in the first chapter Isaiah tells us that the Lord is speaking. ( v 2, 10, 20, 24)

He clearly establishes the problem :
Israel, His Son, has revolted against Him.
They do not know Him.
They don't understand the depth of their trouble.
They are weighed down with sin.
They have abandoned Him, despised Him, turned away from Him.
They are completely sick - from head to toe.
They have lost everything - land, cities, fields... everything!
A clear picture of "all who have sinned and fall short of the glory of God".

Their offerings and sacrifices are not only meaningless, but sickening to the Lord.  They are hypocritical, worthless, and burdensome.
What is truly needed is repentance:  " Wash yourselves, make yourselves clean; remove the evil of your deeds from my sight. Cease to do evil, learn to do good; seek justice, reprove the ruthless; defend the orphan, plead for the widow." 
They need redemption.
They need their scarlet, crimson sins made white.
They need what only God can provide as they come to Him, reasoning - deciding to agree with Him - consenting - willing to obey - hear, perceive , pay attention, and carefully obey Him.

Zion, the beautiful city of God had once been faithful, but was now corrupt.
She once was full of justice and righteousness, but was now full of murderers.
She once was like silver, but now like dross.
Her rulers are rebels.
They associate with thieves.
They take bribes.
They chase rewards.
They ignore the orphans and widows pleas.

Therefore God turned away from them and put them through a refiners fire.
But, there will be a day, the Lord promises, when Zion will be redeemed, restored, made righteous and faithful again... for those who repent.
Yet, the unrepentant will " come to an end".

What do we hear the Lord saying to us ?
Outward religious behavior is sickening to the Lord.  Only in relationship with Him, consenting to do His will - to remove evil, do good, seek justice, reprove those in rebellion, defend the needy - only when we have been washed by the blood of Jesus, the only way our crimson sins can be made white as snow - can we enter Zion, the City of God!

Paul repeats this to his readers in Romans 12:1-2 " I urge you  brethren by the mercies of God, to present your bodies a living and holy sacrifice acceptable to God which is your spiritual service of worship. And do not be conformed to this world but be transformed by the renewing of your mind, that you may prove what the will of God is, that which is good and acceptable and perfect."

Father, once again I thank You for redemption through the Lord Jesus Christ, who has made a way for us to come to You.   I lay down myself, my body, as a willing servant, redeemed and set free from sin, to dwell in the shelter of Your Presence forever.  Bless Your Name forever!  Keep my eyes on Your Majesty and Glory that I might know You more and have understanding and wisdom to walk in Your ways.  I ask this in the Name of my Redeemer and Lord, amen.