Is it more scriptural to use unleavened bread at the Lord's Supper since leaven in Scripture always typifies sin?

No. The Lord's Supper was instituted at the end of the Passover feast. Therefore, we could assume that the Lord used the type of bread which was readily available. By necessity, this would have been unleavened bread, the only bread allowed at the Passover feast (Exodus 12:15). However, this fact does not justify the sole use of unleavened bread at the Lord's Supper. The following reasons explain why it is not more scriptural to use unleavened bread than leavened bread at the Lord's Supper.

We find that two different Greek words are used for bread in the New Testament—artos and azumos. Artos signifies a small loaf or cake composed of flour and water, baked in an oblong or round shape and about as think as the thumb. Artos is also used for bread of any kind (Matthew 16:11) and for food in general (Matthew 6:11). Azumos means unleavened bread—bread without any process of fermentation. It is used metaphorically of a holy, spiritual condition and of sincerity and truth (1 Corinthians 5:7,8). It is also used when designating the feast of unleavened bread. (Note: The above remarks taken from W.E. Vine's Expository Dictionary of New Testament Words.)

Whenever the Lord's Supper (often called the breaking of bread) is mentioned in Scripture, the word artos is used. This even holds true at the institution of the Lord's Supper given to us in the gospels (Matthew 26:26; Mark 14:22; Luke 22:19; Acts 2:42; Acts 20:7; 1 Corinthians 10:16; 1 Corinthians 11:23,26-28). If the Lord intended us to use unleavened bread at the Lord's Supper, the Holy Spirit would have directed the writers to use the word azumos (unleavened bread) instead of artos (bread) in these verses.

In the Old Testament, God's people were forbidden to eat leavened bread or to have it in their houses during the seven days of the Passover feast (Exodus 12:15). For that period of seven days, leaven was seen as a type of sin and therefore could not be used or eaten. The unleavened bread typified holiness, sincerity and truth which should ever characterize God's people (1 Corinthians 5:8).

In the New Testament, God's people are never forbidden to eat leavened bread nor to have leaven in their houses. It is important to see that though the physical use of leaven (or yeast as we would call it today) is never forbidden in the New Testament, yet the spiritual value of leaven as a type of sin remains (Matthew 13:33; Luke 12:1; 1 Corinthians 5:6-8). Therefore, when leaven is mentioned in the New Testament, I am reminded of the spiritual lesson in leaven as a type of sin but never of the physical prohibitions connected with its use in the Old Testament. I quote from one who has made the following observation about types. "There is a general principle relating to Biblical typology: what was once typical as to its literal usage retains its spiritual value as a type when the literal usage as a type has passed away with the legal system."

As a reminder, I would add that in the Lord's Supper the Lord has directed our hearts not to the bread's composition—leavened or unleavened; nor to its color—dark or white; nor to its shape—oblong, round or square, but to what the bread symbolizes—"This is My body which is given for you: this do in remembrance of Me" (Luke 19:22). We can thank Him that His precious body was and is sinless and holy. It is, however, not the physical composition of the bread that would remind us of that blessed truth but the Scriptures themselves!