Believers lost their strength (Christ) in tribulation much like Samson whose strength was in his hair. Let's examine.
POWER AND STRENGTH: CHRIST?
Ps 22:19 But be not thou far from me, O LORD: O my strength, haste thee to help me.
Lu 4:36 And they were all amazed, and spake among themselves, saying, What a word is this! for with authority <1849> and power <1411> he commandeth the unclean spirits, and they come out.
Lu 9:1 Then he called his twelve disciples together, and gave them power <1411> and authority <1849> over all devils, and to cure diseases.
Re 12:10 And I heard a loud voice saying in heaven, Now is come salvation, and strength <1411>, and the kingdom of our God, and the power <1849> of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.
2Sa 22:33 God is my strength and power: and he maketh my way perfect.
Ps 37:39 But the salvation of the righteous is of the LORD: he is their strength in the time of trouble.
Isa 33:2 O LORD, be gracious unto us; we have waited for thee: be thou their arm every morning, our salvation also in the time of trouble.
Ps 68:35 O God, thou art terrible out of thy holy places: the God of Israel is he that giveth strength and power unto his people. Blessed be God.
Job 26:2 How hast thou helped him that is without power? how savest thou the arm that hath no strength?
Ps 65:6 Which by his strength setteth fast the mountains; being girded with power:
Heb 1:2 Hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds;
Isa 40:29 He giveth power to the faint; and to them that have no might he increaseth strength.
Da 2:37 Thou, O king, art a king of kings: for the God of heaven hath given thee a kingdom, power, and strength, and glory.
Ho 12:3 He took his brother by the heel in the womb, and by his strength he had power with God:
Pr 31:3 Give not thy strength unto women, nor thy ways to that which destroyeth kings.
Re 5:12 Saying with a loud voice, Worthy is the Lamb that was slain to receive power <1411>, and riches, and wisdom, and strength, and honour, and glory, and blessing.
FAILED STRENGTH: ELECT IN TRIBULATION?
Re 17:13 These have one mind (10 horns), and shall give their power <1411> and strength <1849> unto the beast.
Re 17:17 For God hath put in their hearts to fulfil his will, and to agree and give their kingdom unto the beast, until the words of God shall be fulfilled.
La 1:6 And from the daughter of Zion all her beauty is departed: her princes are become like harts that find no pasture, and they are gone without strength before the pursuer.
Jer 20:5 Moreover I will deliver all the strength of this city, and all the labours thereof, and all the precious things thereof, and all the treasures of the kings of Judah will I give into the hand of their enemies, which shall spoil them, and take them, and carry them to Babylon.
Ps 78:61 And delivered his strength into captivity, and his glory into the enemy’s hand.
Na 3:11 Thou also shalt be drunken: thou shalt be hid, thou also shalt seek strength because of the enemy.
La 1:14 The yoke of my transgressions is bound by his hand: they are wreathed, and come up upon my neck: he hath made my strength to fall, the Lord hath delivered me into their hands, from whom I am not able to rise up.
Ps 71:9 Cast me not off in the time of old age; forsake me not when my strength faileth <03615>.
Ps 31:10 For my life is spent <03615> with grief, and my years with sighing: my strength faileth because of mine iniquity, and my bones are consumed.
Isa 49:4 Then I said, I have laboured in vain, I have spent <03615> my strength for nought, and in vain: yet surely my judgment is with the LORD, and my work with my God.
Ps 38:10 My heart panteth, my strength faileth me: as for the light of mine eyes, it also is gone from me.
Jud 16:17 That he told her all his heart, and said unto her, There hath not come a razor upon mine head; for I have been a Nazarite unto God from my mother’s womb: if I be shaven, then my strength will go from me, and I shall become weak, and be like any other man.
Ps 73:26 My flesh and my heart faileth: but God is the strength of my heart, and my portion for ever.
Ro 5:6 For when we were yet without strength, in due time Christ died for the ungodly.
Isa 37:3 And they said unto him, Thus saith Hezekiah, This day is a day of trouble, and of rebuke, and of blasphemy: for the children are come to the birth, and there is not strength to bring forth.
Da 10:8 Therefore I was left alone, and saw this great vision, and there remained no strength in me: for my comeliness was turned in me into corruption, and I retained no strength.
Da 11:31 And arms shall stand on his part, and they shall pollute the sanctuary of strength, and shall take away the daily sacrifice, and they shall place the abomination that maketh desolate.
De 32:36 For the LORD shall judge his people, and repent himself for his servants, when he seeth that their power is gone, and there is none shut up, or left.
Da 12:7 And I heard the man clothed in linen, which was upon the waters of the river, when he held up his right hand and his left hand unto heaven, and sware by him that liveth for ever that it shall be for a time, times, and an half; and when he shall have accomplished to scatter the power of the holy people, all these things shall be finished.
The Bible appears to be associating the ten horn giving their power and strength unto the beast to the killing of the two witnesses. Time when the church is without strength (Christ) before the enemy. Then at the revelation of Christ, the elect receive strength while the unsaved continue to be eternally without strength.