The term "backslider in heart" refers to an individual who has turned away from their devotion and commitment to God, not necessarily through overt actions, but through a gradual decline in their spiritual fervor and love for God. This concept is rooted in the understanding that one's heart, the center of one's being and affections, can drift away from God even if outward appearances remain unchanged.

Biblical References:

The concept of backsliding is addressed in several passages throughout the Bible, highlighting the spiritual dangers and consequences of a heart that turns away from God.

1. Proverbs 14:14 : "The backslider in heart will be filled with the fruit of his own ways, but a good man will be rewarded for his." This verse contrasts the outcomes of a backslider with those of a righteous person. The backslider reaps the consequences of their spiritual decline, while the righteous receive blessings for their steadfastness.

2. Jeremiah 3:22 : "Return, O backsliding children, and I will heal your backslidings." Here, God calls His people to repentance, offering healing and restoration to those who have turned away from Him. This demonstrates God's desire for reconciliation and His willingness to forgive those who return to Him with a repentant heart.

3. Hosea 14:4 : "I will heal their apostasy; I will freely love them, for My anger has turned away from them." This passage emphasizes God's grace and mercy towards those who have backslidden, promising healing and love to those who repent.

Characteristics of a Backslider in Heart:

1. Loss of First Love: A backslider in heart often experiences a waning of their initial passion and love for God. Revelation 2:4 warns the church in Ephesus, "But I have this against you: You have abandoned your first love."

2. Neglect of Spiritual Disciplines: Prayer, Bible study, and fellowship with other believers may become neglected, leading to a weakened spiritual state. Hebrews 10:25 encourages believers not to forsake assembling together, recognizing the importance of community in maintaining spiritual vitality.

3. Compromise with Sin: A backslider may begin to tolerate or justify sinful behaviors that they once rejected. James 4:4 warns, "You adulteresses! Do you not know that friendship with the world is hostility toward God?"

4. Indifference to God's Word: The backslider may become indifferent or resistant to the teachings and convictions of Scripture. Psalm 119:105 states, "Your word is a lamp to my feet and a light to my path," underscoring the importance of Scripture in guiding one's life.

Spiritual Remedies:

1. Repentance: Acknowledging one's backslidden state and turning back to God is the first step towards restoration. 1 John 1:9 assures, "If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness."

2. Renewal of Mind and Heart: Romans 12:2 encourages believers to be transformed by the renewing of their minds, aligning their thoughts and desires with God's will.

3. Recommitment to Spiritual Disciplines: Reengaging in prayer, Bible study, and fellowship can help restore one's relationship with God and strengthen their faith.

4. Seeking Accountability: Engaging with a community of believers who can provide support, encouragement, and accountability is vital for spiritual growth and perseverance.

The journey of a backslider in heart is a cautionary tale of the subtlety of spiritual decline, yet it is also a testament to the boundless grace and mercy of God, who continually calls His children back to Himself.