Why did Samson fall for such dangerous women?

Samson certainly seemed to find the Philistine women attractive!

First there was the woman of Timnah:

Then [Samson] came up and told his father and mother, “I saw one of the daughters of the Philistines at Timnah. Now get her for me as my wife.” 3 But his father and mother said to him, “Is there not a woman among the daughters of your relatives, or among all our people, that you must go to take a wife from the uncircumcised Philistines?” But Samson said to his father, “Get her for me, for she is right in my eyes.” (Judges 14:2-3)

There was a prohibition against marriage with the pagan people of Canaan (Deut 7:1,3), which is why Samson’s parents were disappointed with his choice. It seems Samson had trouble controlling his sexual drive and thought the Philistine women were more attractive than the local Israelites.  God used Samson’s moral failure to achieve his own purposes.

Later, Samson fell for a Gazan prostitute (Judges 16:1) and again God used the occasion to punish the Philistines. Then he fell for the scheming Delilah (Judges 16:4-22) which led to his imprisonment and torture. Despite this, God again used Samson to bring about the death of many Philistines (Judges 16:23-30).

The story of Samson teaches us several important lessons:

1. God can even use our weakness and sin for his own purposes. (Of course, he would rather we were faithful and obedient, but when we are not he sometimes uses the opportunity to achieve his own ends..)
2. Samson had some very obvious failings and yet he continued to have faith in the one true God. As a result, he is promised salvation (Hebrews 11:32). This provides great hope to all of us. Despite our human failings and sin, we can receive forgiveness and salvation if we trust in God.
3. God hates idolatry and paganism. In this era of tolerance and pluralism, it is easy to forget that God calls all human beings to worship and obey him. Paul wrote to the church in Thessalonica:
   

   … when the Lord Jesus is revealed from heaven with his mighty angels in flaming fire, inflicting vengeance on those who do not know God and on those who do not obey the gospel of our Lord Jesus.  (2 Thessalonians 1:7-8)

   We are not free to do as we please in religion–there will be consequences for our choices.

Incidentally, the prohibition against marrying unbelievers is still relevant. For example, in discussing the situation of widows, Paul wrote “But if her husband dies, she is free to marry anyone she wishes, but he must belong to the Lord.” (1 Cor 7:39). More generally he wrote “Do not be yoked together with unbelievers”  (2 Cor 6:14). Samson suffered considerably by not obeying this command.