The Lord opened her heart

A common allegory used in the Bible to describe the process of conversion is that of a seed that gets sown in the ground.  In Mark 4 Jesus tells the story of a sower who sows seeds.  Some seed landed on the ground and was immediately eaten by birds.  Some seed landed on rocky ground and so could not take root and was quickly scorched by the hot sun.  Other seeds fell among thorns which choked them off.  But some seeds fell on good fertile soil and produced a massive harvest.  The seed to which Jesus is referring is the message, called the Gospel, that Jesus is the Lord and Savior of the world (Mark 4:14).  The ground the seed lands on is the heart, and the hospitable condition of the heart is critical to the message's ability to take root and grow fruitfully.

Unfortunately due to sin the ground this seed lands on is dead (Ephesians 2:1).  It is inhospitable to spiritual life and the message cannot and will not take root.  Paul wrote, "The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned." (1 Corinthians 2:14)  Who is the natural person?  Anyone who has not been "born again" by the Holy Spirit (John 3:5-6).  How does someone become born again?

The Pharisee Nicodemus asked Jesus this exact question.  Nicodemus asked, "How can a man be born when he is old? Can he enter a second time into his mother's womb and be born?" (John 3:4)  Jesus responded, "Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. That which is born of the flesh is flesh, and that which is born of the Spirit is spirit." (John 3:5-6)  Notice Jesus said "unless one is born of water and the Spirit"...  Being "born again" is described as a two-part process performed on the sinner: 1) being washed and cleansed and 2) being renewed.  In Ezekiel 36, God tells Israel He will first sprinkle clean water on them to cleanse them and then He will renew their heart by removing their heart of stone and replacing it with a heart of flesh:

25 I will sprinkle clean water on you, and you shall be clean from all your uncleannesses, and from all your idols I will cleanse you. 26 And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh. 27 And I will put my Spirit within you, and cause you to walk in my statutes and be careful to obey my rules.  Ezekiel 36:25-27

Likewise, in Titus 3:5 we are told God saved us "according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit".

The point here is in our natural state our hearts are hardened, dead, and unable to respond positively to the message of the gospel.  The truth of the gospel will not make sense to us unless the Holy Spirit first does a work of preparation on our hearts.  Jesus told his disciples, "It is the Spirit who gives life; the flesh is no help at all." (John 6:63)  In Acts 16, we are told the story of when Paul journeyed to Philippi.  He spoke and a women named Lydia heard him.  We are told, "The Lord opened her heart to pay attention to what was said by Paul" and she was later baptized.  The Lord opened her heart.