Pentecost is unique among the holy days because it is the only annual feast determined by counting. All the other festivals God commands us to keep on certain dates on the Hebrew calendar, but we must count for Pentecost. Whether we count fifty days or seven weeks or seven Sabbaths from the day of the wavesheaf offering, we must still go through the exercise of measuring the time to keep the feast properly. Why?
God does nothing without a purpose, and His purposes always include giving His people additional instruction for their ultimately eternal benefit. Counting to Pentecost is no exception. Even a cursory examination will expose several fascinating avenues of study.
First, God commands us to count. Counting is a means of calculating sequential items, events, and measurements. The Bible equates counting to numbering and measuring, and it becomes a metaphor for judging and evaluating. When we understand what the period from the wavesheaf offering to Pentecost represents, the extended meanings come into play.
Passover symbolizes our redemption from this world and the forgiveness of our sins. Unleavened Bread typifies our lifelong task of coming out of sin and putting on the new man in sincerity and truth. We begin to count on wavesheaf day, which occurs during this period, and the fifty days extend to Pentecost, a festival that prefigures the harvest of God's firstfruits. The fifty days, then, represent the period of a Christian's conversion, the time between his calling and his resurrection to eternal life.
Thus, God wants us to count, number, or measure the time of our conversion. This should bring several well-known verses to mind. For instance, Paul considers us wise if we are "redeeming the time, because the days are evil" (Ephesians 5:16). He cautions the Romans, "And do this, knowing the time, that now it is high time to awake out of sleep; for now our salvation is nearer than when we first believed" (Romans 13:11). In both instances, he is advising Christians to measure and make use of our time carefully.
A few Old Testament verses may be even more on point. David writes in Psalm 39:4, "LORD, make me to know my end, and what is the measure of my days, that I may know how frail I am." If we understand just how short our time is, we also realize how weak and insignificant we are next to God and eternity. It forces us to rely upon Him and strive to improve. This is the kind of attitude that God desires in us and will enhance our growth in character.
Moses, too, makes use of this imagery in Psalm 90:12: "So teach us to number our days, that we may gain a heart of wisdom." Properly evaluating our lifetimes builds wisdom in us, and wisdom—the godly use of knowledge and understanding—will make our behavior pleasing to God. Wisdom will help us to prioritize our time properly so we can devote ourselves to what is truly important.
Second, God has us count fifty days. What is significant about the number fifty? Fifty is the round number of years human beings live in a normal adult life (compare Numbers 1:3; Psalm 90:10). Fifty years, then, represents the period during which we live, grow, overcome, bear fruit, and prove our devotion to God through trials, tests, blessings, curses, and life's other varied experiences. Fifty years corresponds to the span of our conversion.
Biblically, the number fifty has its closest association with two things: the Tabernacle/Temple (in some of its measurements) and the Jubilee. The apostles describe God's church as a temple, and Christians are individual "living stones" within it (I Corinthians 3:9, 16-17; Ephesians 2:19-22; I Peter 2:5). The fifty days thus symbolize the time it takes to complete the work of building a habitation for God.
Every fiftieth year in ancient Israel, the Jubilee was decreed on the Day of Atonement (Leviticus 25:8-9), which, among other things, represents unity, being at one, with God. The Jubilee was a year of liberty, when all debts were cancelled and inheritances reverted to their original families (verse 10), foreshadowing "the restoration of all things" (Acts 3:21). It was also a year of rest (Leviticus 25:11), when no crops were sown or reaped, a foretaste of God's rest (Hebrews 4:4-10). Under this type, the fiftieth day of the count, Pentecost, represents the harvest of Christians into God's Kingdom by the resurrection.
Overall, then, we count to Pentecost for two major reasons:
In His wisdom, God has us annually take stock of our procession through time so that we will devote ourselves to making the most of it. In doing so, we can gauge our progress toward God's Kingdom.