Judges 13

3 This experience appears similar to what happened to Mary and other women who had special sons (Luke 1:30-31).
4 Num 6:2-22 describes the rules of being a Nazirite, or one separated for devotion to God. The primary irony here seems to be that Samson would hardly be considered a "holy man" to the outside observer. However, Samson's life does prove that God can use anyone in His plans. In the end it is Samson's true faith in God that finally deals the decisive blow to the Philistines.
6 When the woman faced God she was so amazed that she was speechless. Others who have had God encounters do manage to ask a few questions, but the primary purpose of such visitations is for God to inform people what He is about to do.
7 Most Nazirite vows only lasted a relatively short time, but Samson was to be so devoted to God from the moment of conception until he died.
8 We can understand Manoah's concern since they had never had to raise children, much less a child that would need special rules and attention. But even so, all parents should pray that God would help them raise their children. They may not get a special visitor, but God has given them the Bible as a guidebook.
12 The question may seem comical or beside the point, but in fairness, Manoah is asking about the purpose for this special child. Would he be an agricultural man (as was likely Manoah), or was he to become a full time priest? How should he train his son? Perhaps since God had already determined that Samson would be a Nazirite He would also give the father more details on how he was to raise the boy. God did not answer his question, but simply reiterated a few of the rules of the Nazirite.

To a certain degree, the same still holds true today. God tells all Christians to live a holy and devoted life, but He does not map out things like occupation, marriage, location, etc. God made us intelligent beings with the ability to make many of our own decisions in life will depending on God for help and guidance. If we are living in accordance with God's word, it makes little difference what our vocation might be.

13 God speaks to the woman because she is ready to listen and obey. The man is too concerned about his own questions. God already knows our questions, and we are very good at asking them, but even more importantly, we need to learn how to listen to God.