Well, what does the Scripture say?
Rom. 9
10 And not only this, but when Rebecca also had conceived by one man, even by our father Isaac 11 (for the children not yet being born, nor having done any good or evil, that the purpose of God according to election might stand, not of works but of Him who calls), 12 it was said to her, The older shall serve the younger. 13 As it is written, Jacob I have loved, but Esau I have hated. 14 What shall we say then? Is there unrighteousness with God? Certainly not! 15 For He says to Moses, I will have mercy on whomever I will have mercy, and I will have compassion on whomever I will have compassion. 16 So then it is not of him who wills, nor of him who runs, but of God who shows mercy. 17 For the Scripture says to the Pharaoh, For this very purpose I have raised you up, that I may show My power in you, and that My name may be declared in all the earth. 18 Therefore He has mercy on whom He wills, and whom He wills He hardens.
19 You will say to me then, Why does He still find fault? For who has resisted His will? 20 But indeed, O man, who are you to reply against God? Will the thing formed say to him who formed it, Why have you made me like this? 21 Does not the potter have power over the clay, from the same lump to make one vessel for honor and another for dishonor?
22 What if God, wanting to show His wrath and to make His power known, endured with much longsuffering the vessels of wrath prepared for destruction, 23 and that He might make known the riches of His glory on the vessels of mercy, which He had prepared beforehand for glory, 24 even us whom He called, not of the Jews only, but also of the Gentiles?
By this passage (vrs. 21 & 22), it would appear that God chooses some for honor, and does indeed choose some for destruction. Verse 16 indicates that our will doesn't even come into play. It's totally of God, who shows us mercy. We were spiritually dead (Eph. 2:1), unable to respond to anything (Eph. 4:18). What response can a dead person give? But by God's mercy and of His own choosing, we are born again, of the spirit, as Jesus tried to explain to Nicodemus (John 3); made alive spiritually (Eph 2:4-5). God orchestrates our lives, bringing us to a decision point, and quickening our spirits, he opens our eyes such that we actually have no choice but to believe. Praise God for that.
But He does choose some for dishonor and destruction. Some are destined for hell. This is indeed a hard teaching. Is God unrighteous? No. (vrs. 14) God is sovereign and He has His purposes (vrs 11). Who are we to question (vrs. 20)? He does so to show His glory and mercy to those whom He calls (vrs. 23). Let us always be thankful for His mercy to us.
So, in light of the fact that it is God that chooses and that He has already done so, even before people are born (vrs. 11), does that mean that we have no need to spread the gospel? No, it doesn't. We should never stop witnessing, because we may be the instrument by which He has chosen to extend mercy to another.