Take Isaiah 49:1-6 as an example: 

Isaiah 49:1–6 (ESV)

¹ Listen to me, O coastlands, and give attention, you peoples from afar. The Lord called me from the womb, from the body of my mother he named my name. ² He made my mouth like a sharp sword; in the shadow of his hand he hid me; he made me a polished arrow; in his quiver he hid me away. ³ And he said to me, “You are my servant, Israel, in whom I will be glorified.” ⁴ But I said, “I have labored in vain; I have spent my strength for nothing and vanity; yet surely my right is with the Lord, and my recompense with my God.” ⁵ And now the Lord says, he who formed me from the womb to be his servant, to bring Jacob back to him; and that Israel might be gathered to him— for I am honored in the eyes of the Lord, and my God has become my strength— ⁶ he says: “It is too light a thing that you should be my servant to raise up the tribes of Jacob and to bring back the preserved of Israel; I will make you as a light for the nations, that my salvation may reach to the end of the earth.”

To what is Isaiah referring? 

Maybe…

Israel: Yahweh called Israel from the womb, that is, He fashioned and molded them as a nation (v. 1). He raised them and nurtured them cf. Hos. 11) and He established them (v. 2). Israel was created to show the glory of God (v. 3). Israel will fulfill its purpose, even by being a light to the nations and the beacon of salvation to the ends of the earth (vv. 4-6).  

Remnant of Israel: All those who were “afar,” lost in exile (v. 1) would be called home. God formed Israel, and so God could reform Israel (vv. 1-3). The return of Israel would further bring glory to God (v. 3). In the face of despair, they could retain their fidelity and trust in God to deliver them (v. 4). God formed them, He could bring them back and build them up, and make them a beacon of hope for all others seeking salvation (vv. 5-6). 

Jesus: Jesus, God incarnate was formed in the womb to take on flesh (cf. Gal. 4:4; Phil. 2:5-7). Although He existed pre-incarnate, He was born of a woman in the flesh to be the preeminent Servant of Yahweh God (vv. 1-3). He would have a mouth like a sharp sword and He would be the polished arrow (v. 2). In Him God would be fully and entirely glorified (v. 3; cf. John’s gospel). Jesus would be the servant, the One honored in the eyes of God, the strength-giver, the One who raises up and preserves, and stretches out light and salvation (vv. 4-6).

The church: God formed the church, establishing it and creating it (v. 1; cf. Matt. 16:18). The church is a platform through which the world is instructed and taught, like the mouth and hand used in v. 2. The church is the servant, not organizationally but organically. Through the church, God is supremely glorified (v. 3; cf. Eph. 3:10-11). The church then, exists to bring back all to God, to honor God, and to be strengthened by God (v. 5). The church raises those who desire to return to God, and shine a light to the lost, preaching salvation even to the end of the earth (v. 6). 

Which is it? 

Could there be a sense in which it is more than one? Perhaps. Surely there was a singular meaning in mind when the words were penned, but everything takes on a new meaning after Christ Jesus. 

Of course, this text and the other Servant Songs (e.g., 42:1-9; 50:4-9; 52:13-53:12), all find their greatest fulfillment in the person of the Messiah Jesus Christ. There can be no clearer explanation than Jesus Christ. 

“When the Servant’s mission is considered (42:1-9), it becomes clear that only the Christ fulfilled the assignment; all others fall short. He alone is the instrument of Israel’s restoration and redemption, a light to the Gentiles, and the establisher of justice on the earth. Also, the means He used in accomplishing His mission sets Him apart from any of the other suggestions” (Homer Hailey, A Commentary on Isaiah: With Emphasis on the Messianic Hope [United States: Religious Supply Inc., 1992] 351-352).