Your own heart & faith | Guard your heart

Date: 12 Octo­ber 2025 | Pre­a­cher:
Series: | Bible text: Pro­verbs 4:23
Hint: This ser­mon has been machi­ne trans­la­ted. Plea­se note that we can­not accept any respon­si­bi­li­ty for the accu­ra­cy of the content.

As with a pre­cise con­trol sys­tem, it is the heart that deter­mi­nes func­tion or mis­be­ha­viour in life. The Bible warns: «More than any­thing else, guard your heart.» A har­den­ed heart comes from unbe­lief, doubt and rebel­li­on; an undi­vi­ded heart comes from trust, faith and devo­ti­on. Tho­se who look to the unseen and obey God’s voice expe­ri­ence his strength, peace and joy – and remain inward­ly ali­ve and spi­ri­tual­ly receptive.


In my pre­vious job, I built con­trol sys­tems for auto­cla­ves. An auto­cla­ve is a gas-tight, sealable pres­su­re ves­sel that is used to ste­ri­li­se mate­ri­als and instru­ments using steam under high pres­su­re. At first glan­ce, you might think that the eye-cat­ching pres­su­re ves­sel is the cen­tre­pie­ce of such an appa­ra­tus. Howe­ver, it is actual­ly not the con­tai­ner that deter­mi­nes the effec­ti­ve­ness of the ste­ri­li­sa­ti­on pro­cess, but the con­trol sys­tem. Micro­or­ga­nisms such as bac­te­ria, viru­s­es and spo­res can only be relia­bly kil­led if the con­trol sys­tem works flaw­less­ly. This is why a gre­at deal of time and care is inves­ted in trou­ble­shoo­ting when crea­ting the con­trol software.

It is the same with us humans: The decisi­ve fac­tor for our beha­viour and natu­re is not our visi­ble body, but our heart. It influen­ces our who­le life. That is why Pro­verbs says: «More than any­thing else, guard your heart, for life emana­tes from it» (Pro­verbs 4:23 SLT). The source of life springs from the heart. That is why Solo­mon, the aut­hor of Pro­verbs, recom­mends guar­ding our heart more than any­thing else.

The heart is the very core of the human being – the cent­re of our per­so­na­li­ty, the place of our thoughts, fee­lings, desi­res and decis­i­ons. In the Bible, the heart is not just the seat of our emo­ti­ons, but the con­trol cent­re that deter­mi­nes our enti­re life. That is why God’s Word calls out to us: «More than any­thing else, guard your heart!» Why should we pre­ser­ve it more than any­thing else? So that it does not beco­me slug­gish or proud, har­den­ed or even obdurate.

A hardened heart

The Bible uses various terms for bad sta­tes of heart: a har­den­ed, har­den­ed, proud, wrong or divi­ded heart. The pro­blem of a divi­ded heart is par­ti­cu­lar­ly serious. «Such a man does not think that he will recei­ve any­thing from the Lord, a man with a divi­ded heart, unsta­ble in all his ways» (James 1:7f SLT).

About Pha­raoh it says: «I will har­den his heart» (Exodus 4:21; 10:20, 27). But it is also writ­ten: «Pha­raoh har­den­ed his heart» (Exodus 8:11, 28). Alt­hough he admit­ted that he had sin­ned against God during the pla­gues of hail and locus­ts and that the LORD was right, his heart remain­ed unte­acha­ble. His obdu­ra­cy was so devas­ta­ting that it ulti­m­ate­ly led to the des­truc­tion of his enti­re army.

What is almost more frigh­tening is that Jesus» disci­ples also had har­den­ed hearts. Jesus men­ti­ons this twice – both times in con­nec­tion with the mul­ti­pli­ca­ti­on of the loaves:

  • After the fee­ding of the 5000 (Mark 6): Jesus com­pels His disci­ples to cross the lake by boat. He wants to pass them on the water in the midd­le of a storm. When they see Him, they are scared to death becau­se they think He is a ghost. «Then he got into the boat and the wind died down. They mar­vel­led at what was hap­pe­ning befo­re their eyes. They still had not rea­li­sed what the mira­cle of the mul­ti­pli­ca­ti­on of the loaves meant, for their hearts were har­den­ed and they did not belie­ve» (Mark 6:52f NLB).
  • Only two chap­ters later, after 4000 peo­p­le had been fed by a mira­cle, Jesus says: «Why are you worried that you have not­hing to eat? Will you never learn or under­stand? Are your hearts too har­den­ed to under­stand?» (Mark 8:17 NLB). The Greek word for «har­den» is poroo and means: to encrust, har­den, dull, beco­me numb.

The reason was that the disci­ples did not under­stand the mira­cle of the mul­ti­pli­ca­ti­on of the loaves spi­ri­tual­ly. How is it pos­si­ble that peo­p­le who lived with Jesus for three years and saw how the dead were rai­sed, lepers cle­an­sed, the sick hea­led and the pos­s­es­sed freed through them had har­den­ed hearts?

If even the disci­ples of Jesus were affec­ted by this, then every fol­lower of Christ should be careful to guard his heart throug­hout his life – so that it does not har­den, but remains ful­ly ori­en­ta­ted towards the Lord.

So what is the «error in jud­ge­ment» of a har­den­ed heart? Accor­ding to the Bible, it is sin, unbe­lief, rebel­li­on, doubt, inse­cu­ri­ty, fear, a focus on the visi­ble and a lack of spi­ri­tu­al dis­cern­ment. With Pha­raoh it was rebel­li­on. For the same reason, God har­den­ed the hearts of his peo­p­le: «And he said, «Go and say to this peo­p­le, «Keep on hea­ring and not under­stan­ding, keep on see­ing and not reco­g­nis­ing. Make the heart of this peo­p­le insen­si­ti­ve, and make their ears hard, and har­den their eyes, so that they will not see with their eyes and hear with their ears, and so that their heart will not come to under­stan­ding and they will not be con­ver­ted and find heal­ing for them­sel­ves!» (Isai­ah 6:9f SLT). Our hearts har­den when the Spi­rit of God speaks to us – and we don’t respond.

An undivided heart

Good sta­tes of heart are a pure, good, sin­ce­re, undi­vi­ded and hum­ble heart. God says to King Asa of Judah: «For the eyes of the LORD roam the who­le earth, to show hims­elf migh­ty in them, who­se heart is undi­vi­dedly set on him. You have acted foo­lish­ly in this; the­r­e­fo­re you will have war from now on!» (2 Chro­nic­les 16:9 SLT). The mes­sa­ge is clear: it is our hearts that deter­mi­ne whe­ther and how we expe­ri­ence God’s power and work. An undi­vi­ded heart recei­ves the bles­sing of God.

Jesus says: «It is cru­cial that you belie­ve and do not doubt it in your hearts» (Mark 11:23 NLB). He explains to Jai­rus: «Do not be afraid. Only belie­ve» (Mark 5:36 NLB). To Peter He says: «You of litt­le faith, why did you doubt?» (Matthew 14:31 LUT). Peter had faith – other­wi­se he would not have been able to rai­se the dead or heal the sick. But Litt­le Faith allo­wed hims­elf to be impres­sed by the visi­ble. Fear and doubt ren­de­red his faith inef­fec­ti­ve.

A har­den­ed heart asks: «What if I pray for this sick per­son and not­hing hap­pens?» But should­n’t we rather ask our­sel­ves: «What if the para­ly­sed per­son gets up? When the tumour dis­ap­pears? When light falls into the dark­ness of depres­si­on?» Smith Wig­g­les­worth (1859–1947), a Bri­tish evan­ge­list and pre­a­cher, expe­ri­en­ced many divi­ne healings. A famous quo­te from him reads: «I am not moved by what I see. I am only moved by what I belie­ve. I know that no one who belie­ves pays atten­ti­on to out­ward appearan­ces. No one who belie­ves thinks about how they feel.» Wig­g­les­worth was not dis­trac­ted by the visi­ble circumstances.

Abra­ham was also a man with an undi­vi­ded heart. God says to him: «I am God Almigh­ty. Live befo­re my face, and be bla­me­l­ess (lite­ral­ly: be whole/undivided with me)!» (Gene­sis 17:1 ELB). Cen­tu­ries later, Abra­ham is descri­bed as a model of faith: «But Abraham’s faith remain­ed unshaken, even though he knew that at almost a hundred years old, he was far too old to beco­me a father and his wife Sarah could no lon­ger have child­ren. Abra­ham did not doubt and trus­ted in God’s pro­mi­se. Yes, his faith even grew, and in doing so he hono­u­red God» (Romans 4:19f NLB). Abra­ham did not doubt, but firm­ly belie­ved in God’s pro­mi­se – that is the mark of an undi­vi­ded heart.

The solution for a hardened heart

It all beg­ins with a clear decis­i­on to ent­rust your who­le life to Jesus Christ. Whoe­ver does this recei­ves a gift: «And I will give you a new heart and give you a new spi­rit. I will take the heart of stone out of your body and give you a heart of fle­sh» (Eze­kiel 36:26 NLB). This is the basis for every undi­vi­ded heart.

When I rea­li­se that my heart has har­den­ed and unbe­lief is so domi­nant, Jesus invi­tes me to rep­ent, expe­ri­ence for­gi­ve­ness and start again.

One of life’s tasks is to «pull the plug» on unbe­lief. Once the disci­ples come to Jesus and ask why they were unable to cast out a demon. Jesus repli­ed «For the sake of your unbe­lief!» (Matthew 17:20 SLT). In other manu­scripts it says «Becau­se of your litt­le faith» (LUT). But the pro­blem was not a lack of faith. Imme­dia­te­ly after­wards, Jesus says that faith, like a grain of mus­tard seed, is enough to move a moun­tain (Matthew 17:21).

It takes a lot of trai­ning to put an end to dis­be­lief. We have to «stretch our heads to the sky. «Sin­ce you have been rai­sed to new life with Christ, seek Christ, who is sea­ted at the right hand of God in hea­ven. Do not think about world­ly mat­ters, but con­cen­tra­te your thoughts on him!» (Colos­si­ans 3:1f NLB). The gaze of faith should be direc­ted towards the hea­ven­ly, invi­si­ble and divi­ne – not towards the earth­ly, visi­ble and transient.

We need each other for this. We should encou­ra­ge each other to speak of the great­ness and pos­si­bi­li­ties of God – to remind our­sel­ves not to look at the visi­ble, but at the invi­si­ble. Other­wi­se, a cree­ping adapt­a­ti­on to the world takes place. If we keep focus­sing on the visi­ble and nega­ti­ve, our hearts harden.

I see this as the main pro­blem in deal­ing with the media and social net­works. They direct our atten­ti­on – and through the algo­rith­ms repea­ted­ly – to the eph­emeral, the visi­ble and the earth­ly. We are dis­trac­ted from the essen­ti­als. We should see through this stra­tegy and resist it. We need spaces of silence. «Be still and reco­g­ni­se that I am God; […] I will be exal­ted on earth!» (Psalm 46:11 SLT). In the silence of God’s pre­sence, we train our­sel­ves to focus on the invi­si­ble, the divi­ne. In silence, we hear God’s voice and all the other voices of this world fade away. In the pre­sence of God, our heart beco­mes hum­ble, soft and undivided.

«More than any­thing else, guard your heart, for life emana­tes from it» (Pro­verbs 4:23 SLT). As with con­trol soft­ware, we must also invest in the pro­per func­tio­ning of our hearts. Our hearts are the con­trol cen­tres that deci­de our enti­re lives. It depends on this whe­ther we lead a life of strength, peace and joy – or drift through life wit­hout expec­ta­ti­ons.

 

Possible questions for the small groups

Bible text: Pro­verbs 4:23; Mark 6:45–52

  1. What does it mean for you per­so­nal­ly to «guard your heart more than any­thing else» (Pro­verbs 4:23)?
  2. How do you reco­g­ni­se in your ever­y­day life that your heart may be begin­ning to har­den or divide?
  3. How can we as Chris­ti­ans learn to focus our gaze on the invi­si­ble – the hea­ven­ly – ins­tead of allo­wing our­sel­ves to be deter­mi­ned by the visible?
  4. What steps help you to over­co­me unbe­lief and doubt and to grow in trust in God’s promises?
  5. What role does silence and time with God play in main­tai­ning a soft and undi­vi­ded heart?