The world finds security in carnal things—temporal situations that are temporary, unreliable, and of low relative value compared to the peace that God offers:
6 ...Lord, lift thou up the light of thy countenance upon us.
7 Thou hast put gladness in my heart, more than in the time that their corn and their wine increased.
8 I will both lay me down in peace, and sleep: for thou, Lord, only makest me dwell in safety. (Psalm 4)
Peace in the world is measured by your goods or tangible situation. If you have lots of money, you feel secure. This is how the world gives peace, and it is completely worthless. Who your friends are, how much money you have, or whether your house is paid off will not protect you from bad things that can happen. The better your temporal situation, the more you have to lose. Worldly peace costs mental peace, and it seems like you can't have both at the same time.
When you realize the fleeting nature of all things here, you cease to seek or find peace in them. Enduring peace comes only from God.
The Lord Jesus said he gives peace, but a different kind of peace than the world purports to give. God's peace is not like what the world calls peace. It is not an externally induced calm or comfort. God’s peace, in contrast, is intrinsic. It comes from inside, and the more of it you have, the harder it is for anything outside of you to affect you.
God's peace has absolutely nothing to do with your temporal situation. You can have the Lord’s peace even when everything in this world seems to be going wrong.
The Lord’s peace can be present in spite of awful external circumstances.
King David was able to have tremendous peace in spite of awful situations that included being hunted for his life, being persecuted by those he had loved at great sacrifice, and living in conditions far poorer than his righteousness merited:
5 Wherefore should I fear in the days of evil, when the iniquity of my heels shall compass me about?
6 They that trust in their wealth, and boast themselves in the multitude of their riches;
7 None of them can by any means redeem his brother, nor give to God a ransom for him:
8 (For the redemption of their soul is precious, and it ceaseth for ever:)
9 That he should still live for ever, and not see corruption.
10 For he seeth that wise men die, likewise the fool and the brutish person perish, and leave their wealth to others.
11 Their inward thought is, that their houses shall continue for ever, and their dwelling places to all generations; they call their lands after their own names.
12 Nevertheless man being in honour abideth not: he is like the beasts that perish.
13 This their way is their folly: yet their posterity approve their sayings. Selah.
14 Like sheep they are laid in the grave; death shall feed on them; and the upright shall have dominion over them in the morning; and their beauty shall consume in the grave from their dwelling.
15 But God will redeem my soul from the power of the grave: for he shall receive me. Selah.
16 Be not thou afraid when one is made rich, when the glory of his house is increased;
17 For when he dieth he shall carry nothing away: his glory shall not descend after him.
18 Though while he lived he blessed his soul: and men will praise thee, when thou doest well to thyself.
19 He shall go to the generation of his fathers; they shall never see light.
20 Man that is in honour, and understandeth not, is like the beasts that perish. (Psalm 49)
He further proclaimed:
3 But thou, O Lord, art a shield for me; my glory, and the lifter up of mine head.
4 I cried unto the Lord with my voice, and he heard me out of his holy hill. Selah.
5 I laid me down and slept; I awaked; for the Lord sustained me. 6 I will not be afraid of ten thousands of people, that have set themselves against me round about. (Psalm 3)
This was not figurative—David’s life was indeed sought by tens of thousands of people on more than one occasion. Yet he maintained tremendous peace.
The Lord’s peace has nothing to do with what things might be happening in your life, or what others are doing. It has everything to do with your relationship with and trust in God.
Stephen had perfect peace when being stoned to death because he trusted in God:
59 And they stoned Stephen, calling upon God, and saying, Lord Jesus, receive my spirit.
60 And he kneeled down, and cried with a loud voice, Lord, lay not this sin to their charge. And when he had said this, he fell asleep. (Acts 7)
He was not alone in this. Paul was joyful in spite of imprisonment, beating, shipwrecks, and a death sentence:
22 And now, behold, I go bound in the spirit unto Jerusalem, not knowing the things that shall befall me there:
23 Save that the Holy Ghost witnesseth in every city, saying that bonds and afflictions abide me.
24 But none of these things move me, neither count I my life dear unto myself, so that I might finish my course with joy, and the ministry, which I have received of the Lord Jesus, to testify the gospel of the grace of God. (Acts 20)
Jeremiah had perfect peace, even when he couldn’t find anyone to listen to his message, which he preached at peril of his life. He still had peace, even when imprisoned in a cesspool.
Peter had perfect peace even when being crucified. Isaiah had perfect peace even while being sawn in half. Countless disciples of Christ had peace while being burned at the stake.
In every case, these people maintained untouchable peace because of their relationship with God. They knew him. They spoke with him. They knew from him their standing with him. They had no doubts as to their eternal posture with God. They did not merely believe that they were in good standing with God, they knew it.
Jesus had peace even when he was surrounded by fools, cowards, betrayers, and those who wanted to kill him. He did not get frustrated when his mission was complicated by the actions (or inactions) of others. He knew that if he was sincerely living up to what he knew was right in all things, he would please the Father, and that was all that mattered to him. His peace came from being able to say: “...the Father hath not left me alone; for I do always those things that please him.” (John 8:29)
The world can’t break God’s promise of peace to those who love him. The Psalmist wrote that “...the Lord will bless his people with peace.” (Psalm 29:11) Paul wrote:
38 For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come,
39 Nor height, nor depth, nor any other creature, shall be able to separate us from the love of God, which is in Christ Jesus our Lord. (Romans 8)
This world is full of turbulence, and it will get worse. Do not buy into any illusion of carnal security. Do not sell your birthright for a bowl of porridge. The only safety is in God's will and word.