If you are a woman and you read Revelation 14:4, and you do not yet have a good understanding of your Heavenly Father, you might think that God views you as contemptible, or less pure than men. However, a child of God is just that, whether male, or female, a child of God.
Rev 14:4(NIV) These are those who did not defile themselves with women, for they kept themselves pure. They follow the Lamb wherever he goes. They were purchased from among men and offered as firstfruits to God and the Lamb.
We are in the habit of viewing everything from our own point of view. However, we are given Scripture in order that we may see as God does. When we consider how God views His children, we can know that He views all of His children the same. Consider Matthew 12:47-50 and this becomes clear.
Mat 12:47-50 (NIV) Someone told him, “Your mother and brothers are standing outside, wanting to speak to you.” He replied to him, “Who is my mother, and who are my brothers?” Pointing to his disciples, he said, “Here are my mother and my brothers. For whoever does the will of my Father in heaven is my brother and sister and mother.”
Of course, the question is “Why did God say men defile themselves with women?”, and the key to understanding is ‘View this from God’s point of view, instead of your own’.
God lives by His own principles and His first and most important rule is “Love the Lord your God with all your heart and with all your soul and with all your mind”. When you know God, you can understand that is how He loves us, with all His heart, soul, and mind. He loves us so much that, if it were possible for God to die, He would die for us.
God wants to become one with everyone. Keeping this in mind, consider 1 Corinthians 6:16 (NIV) Do you not know that he who unites himself with a prostitute is one with her in body? For it is said, “The two will become one flesh.”
God is a jealous God. Exodus 34:14(NIV) Do not worship any other god, for the LORD, whose name is Jealous, is a jealous God.
Considering all of this, can you see that if anyone has sex, or becomes one, with anyone other than God, even if they are married, they are no longer pure in the eyes of God?
It just could be that some of the 144,000 that are spoken of in Revelation 14:1 are women that have not defiled themselves with men.