This chapter defines a special vow a person can take if they want to enter into a special relationship with God. It is not required, but there are always those who wish to take their relationship with God to a higher level. We will read later about Samson, a Nazirite, though not a very successful one. John the Baptist has similarities as well.
There are Christians who to take their commitment to God to higher levels. For instance in Acts 13:3, we are told of Christians fasting and 1 Corinthians 7 speaks of those who are unmarried being better able to focus their attention on God. However, many Christians have done amazing things for God without having experienced special ceremonies or restrictions.