Tainted Offering

Isa 1:12-17
12 "When you come to appear before me, who requires of you this trampling of My courts?13 "Bring your worthless offerings no longer, incense is an abomination to me. New moon and sabbath, the calling of assemblies-- I cannot endure iniquity and the solemn assembly.14 "I hate your new moon {festivals} and your appointed feasts, they have become a burden to me. I am weary of bearing {them.}15 "So when you spread out your hands {in prayer,} I will hide My eyes from you, yes, even though you multiply prayers, I will not listen. Your hands are covered with blood.16 "Wash yourselves, make yourselves clean; remove the evil of your deeds from My sight. Cease to do evil,17 Learn to do good; seek justice, reprove the ruthless; defend the orphan, plead for the widow.(NAS)

Israel was deep in sin at the time that this was written. But the Israelites expected to be able to worship and pray to God in their sin with no change. According to this, that was clearly not the case. God says that he hates their offerings and feasts. Their prayers and offerings had become useless, no matter how numerous they were. They had to cleanse themselves of their sin before they could rightfully worship their holy God.

A similar message is seen in the New Testament.

1 Cor 11:25-2825 In the same way {He took} the cup also, after supper, saying, "This cup is the new covenant in My blood; do this, as often as you drink {it,} in remembrance of Me."26 For as often as you eat this bread and drink the cup, you proclaim the Lord's death until He comes.27 Therefore whoever eats the bread or drinks the cup of the Lord in an unworthy manner, shall be guilty of the body and the blood of the Lord.28 But let a man examine himself, and so let him eat of the bread and drink of the cup.(NAS)

In the same way that the Israelite's sin got in the way of their worship with God, a Christian's sin that he has not repented of can get in the way of his relationship with God. Communion is not just a way to remember Jesus' sacrifice, it is also an opportunity to examine oneself for sin yet to be confessed.