Forgiveness is indeed a Divine action. That implies that unforgiveness and bitterness are from your sin nature and, ultimately, Satan. Forgiveness is one way you can be like God. Without the example and grace of God, how many would ever choose to forgive others? Looking at my life, I know there would be little forgiveness without trusting God's justice and omniscience.

And the consequences of an unforgiving heart are horrible for you.

Unforgiveness: A Barrier to Spiritual Growth

Unforgiveness is a spiritual barrier that hinders our walk with God. As stated in 1 John 4:20-21 (ESV),

"If anyone says, 'I love God,' and hates his brother, he is a liar; for he who does not love his brother whom he has seen cannot love God whom he has not seen. And this commandment we have from him: whoever loves God must also love his brother."

Unforgiveness separates us from enjoying the benefits of dependence on God's wisdom and from growing more of the Fruit of the Spirit in our lives.

Bitterness Defined: The Physical Impact 

Bitterness, often the result of unforgiveness, has a significant impact on our physical health. Psalms 32 (ESV) provides a vivid picture of this impact. David, after his sin with Bathsheba and the murder of Uriah, wrote, 

"Blessed is the one whose transgression is forgiven, whose sin is covered. When I kept silent, my bones wasted away through my groaning all day long. For day and night your hand was heavy upon me; my strength was dried up as by the heat of summer." 

Unforgiveness and the resulting bitterness easily lead to physical suffering, much like David experienced. 

The Consequences of Unforgiveness 

Unforgiveness not only affects our spiritual and physical health but also our emotional well-being. It robs us of joy, freedom, and hope. It consumes our thoughts, controls our actions, and even molds us into the image of the offender.

Unforgiveness can lead to depression, often born from an unhealthy focus on past events, the unfairness of what happened, and the lost hope for justice. It also affects future generations, as research shows parents' unresolved issues pass on to their children. 

Loss of a Walk with God

If someone says, ‘I love God,’ and hates his brother, he is a liar; for he who does not love his brother whom he has seen, how can he love God whom he has not seen? And this commandment we have from Him: that he who loves God must love his brother also. – 1 John 4:20-21

Unforgiveness is never part of walking with God.  Picture Forgiveness and Vengeance as plants.  Forgiveness grows in the soil of the Spirit that produces love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. Vengeance grows in the soil of sin, the same soil from which pride sprouted, leading to Satan’s fall from Heaven. If you have trusted Christ, nothing can take away the gift of eternal life, but your unforgiving spirit separates you from fellowship with God.

Loss of Health and Vitality

God provides healing and blessing through forgiveness, both for those confessing (seeking forgiveness) and those forgiving. But When David did not confess, he suffered physically.

How about you? Are your physical struggles more spiritual than medical? This does not say sin causes sicknesses or physical ailments in your life that forgiveness will cure! But the consequences of unconfessed sin are dire. And, if you refuse to forgive, do not expect to be as healthy and happy as before.

Loss of Joy

It is a simple but sometimes forgotten truth that the greatest enemy to present joy and high hopes is the cultivation of retrospective bitterness. – Robert G. Menzies

The only alternative to forgiveness is vengeance and bitterness. Think about it; there is no middle ground, no matter how you try to avoid the issue. So, ask yourself – do I want to forgive or to be bitter and vengeful?

Do you want the consequences of unforgiveness?

…looking carefully lest anyone fall short of the grace of God; lest any root of bitterness springing up cause trouble, and by this many become defiled… – Hebrews 12:15

Bitterness and vengeance fuel wars and the disputes you have with your enemies. They are probably at the heart of your marriage or family struggle. Bitterness and vengeance always hurt and destroy you as well as others. Forgiveness, though, heals. Which do you want?

Loss of Freedom: Consumed with, Controlled by, and Become Like the Offender

This is possibly the worst of the consequences of unforgiveness, and it is so easy to fall into this trap.

Consumed with the offender – How can you be free when you spend so much time thinking about how they hurt you? Your mind is stuck on trying to resolve something that only God can handle effectively. Spending that much time thinking about them is like building a lovely house for them in your mind and moving them in. You paint and maintain the house because you constantly visit it and THEM.

Controlled by the offender – They not only consume your mind but worse yet, they control you. The longer you carry the grudge, the more they control your thoughts, actions, and feelings. The more you want vengeance, the more energy drains from you as you plot, seek, or try to get revenge. And, even if you get revenge, you often have regrets, second-guesses, or feel it was not enough.

Conformed to be like the offender – Your loss of freedom is complete when your actions reveal that you are becoming like them. Consider this. If you want to learn golf or tennis, you spend time playing and thinking about it. If you want to learn something new, read and think about it. When you immerse yourself in something, it can become part of you. So, the more energy you use and the more time you spend thinking about the person who wronged you, the greater the chance they have to influence your thoughts and actions. You increase the possibility of becoming just like them.

Loss of Hope

Depression is often born from an unhealthy focus on past events. It can be birthed from trying to control a past event, the unfairness of what happened, and the lost hope for justice. Hope, like joy, does not grow from vengeance, bitterness, or holding grudges. Hope takes root in the soil of forgiveness.

Can you right a wrong that has occurred in the past? Of course not! It happened; it is a fact, part of history, and you cannot change it. But you can accept it, learn from it, forgive, and move on because your PERFECT Father God knew about it and will turn it into what is BEST for you as you trust Him.

Loss of Future Generations’ Health

Research shows parents’ unresolved issues pass on to children. In attitude, words, and actions, your bad thinking, whether you know it or not, is passed on to your children; even if they learn from your mistakes and do not repeat them, they will still suffer in other ways for your mistakes. God clearly states this:

…For I, the Lord your God, am a jealous God, visiting the iniquity of the fathers upon the children to the third and fourth generations of those who hate Me – Exodus 20:5

The past is over. Move on! Trust God to redeem your past! He knows what is best for you. And He is using this situation for your best and for the other person's best. Trust His PERFECTION! Doing it any other way will create more problems.

The Path to Freedom: Forgiveness 

In contrast, forgiveness encourages hope and a new future for your life. Ephesians 4:32 (ESV) encourages us to "be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you." Forgiveness puts a new future before you and gives you a new way to see those who hurt you. It may be the one act that allows you to imitate God, the original Master Forgiver. 

There is hope, joy, and blessing if you pay attention to what God says. You saw what God said in Exodus 20:5, but notice what He says in Exodus 20:6.

…but showing mercy to thousands, to those who love Me and keep My commandments. – Exodus 20:6

Conclusion 

Unforgiveness and bitterness are not just spiritual issues; they have tangible impacts on our physical health and overall well-being. By choosing to forgive, we choose freedom, health, and a closer walk with God. We choose to break the cycle of pain and open the door to healing and restoration. As we unmask unforgiveness and define bitterness, we can better understand their impacts and make the conscious choice to live in the freedom that forgiveness offers.