While the Levites were specially chosen by God to serve as priests, the Nazirite vow in Numbers 6 was a way for any person, male or female, from any tribe to dedicate themselves to God for the purpose of serving Him. In fact, the term Nazirite comes from the Hebrew word nāzar, which means "to dedicate". A person taking the Nazirite vow would dedicate themselves to God for a set period of time (usually a month, though, it could last a year or longer). They would be subject to 3 restrictions during their period of dedication: don't drink alcohol (v3-4); don't cut your hair (v5); and don't go near a dead body (v6). Samson was to be a Nazirite for life (Judges 13:7). Paul took the vow for a season (Acts 18:18).
The Nazirite vow is not something that Christians typically make today. (Fasting is perhaps the closest equivalent, where we dedicate ourselves for a set period of time to abstaining from certain foods or drink or other activities in order to draw near to God.) So what can we learn from the Nazirite vow?
1. Don't let your background disqualify you from serving God. Just as anyone from any tribe in Israel could take the Nazirite vow and dedicate themselves to God, you don't need to wait for a special "calling" from God to serve Him. You are already called and chosen by God to serve Him, regardless of how many mistakes you've made in your past or what your background is. The question is not whether you are called to serve God; the question is how seriously do you take God's call on your life and how willing are you to voluntarily give of yourself to serve Him?
2. Exercise self-discipline. Just as a Nazirite made a personal commitment not to consume wine, other fermented drinks or anything from the grapevine, if you want to serve the Lord effectively, you need self-control. Be careful not to be consumed by things that will impair your judgment. You can be very passionate about serving God, but if you don't set healthy boundaries and exercise self-discipline, like Samson who took a Nazirite vow but had no self-discipline, you will severely limit what God can do in and through your life, and you might actually do more harm than good. As 2 Timothy 1:7 says, "For God did not give us a spirit of fear, but a spirit of power, of love, and of self-discipline."
3. Watch the Fruit You Bear. When people saw the Nazirite's uncut hair, it was a sign to them that "This person is a Nazirite, someone dedicated to God". In the same way, when people see you, is there visible evidence of your dedication to God? I'm not talking about the length of your hair. I'm saying: when people look at you, can they tell from your actions, your attitude, your words, your decisions and the way you treat people that you are dedicated to God? Put another way: if living the Christian life was a crime, would there be enough evidence to convict you?
4. Let Christ in you raise the dead to life. In the Old Testament, a Nazirite was not to go near a dead body for fear of defiling himself. But in the New Testament, we see Jesus, who was set apart for service to God, touching dead bodies and raising them to life. So don't go to spiritually dead people and become spiritually dead yourself. Instead, like Jesus, as the church let's go to those who are spiritually dead and let Christ in us raise them to life.