we know that this is indeed the Savior of the world

The Savior, Redeemer

1 Who has believed what He has heard from us?     And to whom has the arm of the Lord been revealed? 2 For He grew up before Him like a young plant,     and like a root out of dry ground; He had no form or majesty that we should look at Him,     and no beauty that we should desire Him. 3 He was despised and rejected by men;     a man of sorrows, and acquainted with grief; and as one from whom men hide their faces     He was despised, and we esteemed Him not.

4 Surely He has borne our griefs     and carried our sorrows; yet we esteemed Him stricken,     smitten by God, and afflicted. 5 But He was pierced for our transgressions;     He was crushed for our iniquities; upon Him was the chastisement that brought us peace,     and with his wounds we are healed. 6 All we like sheep have gone astray;     we have turned—every one—to his own way; and the Lord has laid on Him     the iniquity of us all.

7 He was oppressed, and He was afflicted,     yet He opened not his mouth; like a lamb that is led to the slaughter,     and like a sheep that before its shearers is silent,     so He opened not his mouth. 8 By oppression and judgment He was taken away;     and as for his generation, who considered that He was cut off out of the land of the living,     stricken for the transgression of my people? 9 And they made his grave with the wicked     and with a rich man in his death, although He had done no violence,     and there was no deceit in his mouth.

10 Yet it was the will of the Lord to crush Him;     He has put Him to grief; when his soul makes an offering for guilt,     He shall see his offspring; He shall prolong his days; the will of the Lord shall prosper in his hand. 11 Out of the anguish of his soul He shall see and be satisfied; by his knowledge shall the righteous one, my servant,     make many to be accounted righteous,     and He shall bear their iniquities.

12 therefore I will divide Him a portion with the many,
    and He shall divide the spoil with the strong,
because He poured out his soul to death
    and was numbered with the transgressors;
yet He bore the sin of many,
    and makes intercession for the transgressors.

(from: Isaiah 53 English Standard Version (ESV))

Isaiah 41:14 Fear not, you worm Jacob, you men of Israel! I am the one who helps you, declares the Lord; your Redeemer is the Holy One of Israel.
Isaiah 44:24 Thus says the Lord, your Redeemer, who formed you from the womb: “I am the Lord, who made all things, who alone stretched out the heavens, who spread out the earth by myself,

Isaiah 45:15 Truly, you are a God who hides himself, O God of Israel, the Savior.
Isaiah 45:21 Declare and present your case; let them take counsel together! Who told this long ago? Who declared it of old? Was it not I, the Lord? And there is no other god besides me, a righteous God and a Savior; there is none besides me.
Isaiah 49:26 I will make your oppressors eat their own flesh, and they shall be drunk with their own blood as with wine. Then all flesh shall know that I am the Lord your Savior, and your Redeemer, the Mighty One of Jacob.”
Isaiah 60:16 You shall suck the milk of nations; you shall nurse at the breast of kings; and you shall know that I, the Lord, am your Savior and your Redeemer, the Mighty One of Jacob.
Isaiah 48:17 Thus says the Lord, your Redeemer, the Holy One of Israel: “I am the Lord your God, who teaches you to profit, who leads you in the way you should go.
Isaiah 54:8 In overflowing anger for a moment I hid my face from you, but with everlasting love I will have compassion on you,” says the Lord, your Redeemer.         
Isaiah 59:20 “And a Redeemer will come to Zion, to those in Jacob who turn from transgression,” declares the Lord.

___________Who is This Savior, Redeemer?
Luke 2:11
For unto you is born this day in the city of David a Savior, who is Christ the Lord.
Luke 2:10-12 (in Context) Luke 2 (Whole Chapter) Other Translations

John 4:42 They said to the woman, “It is no longer because of what you said that we believe, for we have heard for ourselves, and we know that this is indeed the Savior of the world.”  

John 4:41-43 (in Context) John 4 (Whole Chapter) Other Translations

Acts 5:31 God exalted him at his right hand as Leader and Savior, to give repentance to Israel and forgiveness of sins.
Acts 5:30-32 (in Context) Acts 5 (Whole Chapter) Other Translations
Acts 13:23 Of this man's offspring God has brought to Israel a Savior, Jesus, as he promised.
Acts 13:22-24 (in Context) Acts 13 (Whole Chapter) Other Translations

Jesus Messiah, the Redeemer, Savior