THE TEMPLE CURTAIN
According to Mark 15:37-39, when Jesus Christ died, the temple curtain was miraculously torn in two, from top to bottom. In order to understand why this should be so significant, one must first understand the importance of this curtain.
To begin with, the temple was a permanent version of the original Holy Tabernacle. What was this tabernacle?
The Tabernacle was a large, tent-like house of worship for the Israelites (Exodus 25:9) (KJV) and was constructed exactly to God's specifications (Exodus 25-27). Part of those specifications included inner room divisions: A Holy room, and a Most Holy (or Holy of Holies) room, which were to be separated by a thick curtain (Exodus 26:33). The common people weren't allowed in the Holy; only the Levite Priests were allowed to enter the Holy (Exodus 28:35, 43). The Levite Priests were not allowed to enter the Most Holy, only the High Priest was allowed to enter, and only once per year -- on the Day of Atonement (Exodus 30:10, Hebrews 9:7). If the High Priest entered the Most Holy at any other time he would die (Leviticus 16:2). The Most Holy room housed the Ark of the Covenant (Exodus 26:34).
The Temple was a permanent version of the Tabernacle and was located in Jerusalem (Ezra 5:15), because God chose Jerusalem to be His holy city (1 Kings 9:3, 14:21). King Solomon organized the construction of the temple (1 Kings 6). When the temple was built, it was built in the fashion of the Tabernacle, including the rooms of the Holy and the Most Holy (1 Kings 6:17, 7:50), divided by the thick curtain. The temple was intended to be an earthly copy of God's Heavenly Temple (Hebrews 9:24).
This curtain between the Holy and the Most Holy represented the division between God's pure holiness and mankind's unclean sinfulness. This division occured when Adam and Eve sinned by breaking God's commandment, requiring them to be banished from God's specially created garden (Genesis 3). Since sin is dirty, and you cannot get something clean from something dirty, every person born from them inherited the filthiness of sin. Sin cannot stand in the presence of Holiness (Habakkuk 1:13). This is why God commanded that there be a separate Most Holy place in His house of worship, and why He commanded strict rules regarding the Holy and the Most Holy (Exodus 26:34, 28:35, 43, 30:31-32, 37, etc.).
Those who sin owe death for their sins (Romans 6:23). Because there are no sinless people, this would become an endless cycle of life and death for the entirety of mankind. God had a better plan: The death of a sinless man would serve to absorb others' sins because a sinless man does not owe death for anything; ergo, his undeserved death could serve to absorb the sins of everyone else. This is why Jesus Christ was sent to earth: To be a sinless human (Hebrews 4:14-15, 9:14) that would die in our stead. Because he didn't owe death for himself, his death served to cover our sins. Just as death came to mankind through one man (Adam), so to life was restored through one man (Jesus Christ) (Romans 5:12-17, 1 Corinthians 15:22). Because Jesus did this for us, he can be referred to as the "Last Adam" (1 Corinthians 15:45). A sinless man's death cannot be "used up", therefore, infinite sinners can be covered.
Because Jesus Christ's death cleanses us from sin (Hebrews 9:11-14), he is the bridge, or the mediator, between mankind and God (1 Timothy 2:5). (This is why we must pray to the Father in the name of Jesus -- John 14:13). Because his death bridged our separation from God, the temple curtain was completely torn from top to bottom upon his death -- a visual sign to show that, now, anyone who believed had access to God, no more barrier to the Most Holy (Hebrews 10:19-22).
To sum it all up, it all boils down to this: Our sinful nature creates a barrier between us and God, as symbolized by the temple curtain. Jesus Christ came and removed that barrier so that we can be clean in the sight of God, further symbolized by the destruction of the temple curtain.
Let none of us make a mockery of this awesome opportunity; continue living as God's holy people, and do what we can to lead others to this splendid chance for redemption.