(paraphrasing)For everyone - including you - who are concerned about "all the heathen" who don't know about Jesus and who, therefore, are headed for hell (which is eternal separation from GOD - whose son, Jesus, is very God and very Man - the God-man) - he says the surest way to ease your worry is to be sure you are not a part of them. Come in - take Jesus Christ as your SAvior and Lord - and then He will send you out to bring as many of "the heathen" to Him before they die!
He further says that the Word of God is crystal clear: No one comes to the Father except they come through Jesus Christ. In other words, there is no way to eternal life with God except through Jesus Christ. Lewis also reminds us that in the letter to the Romans, we see that somehow, in God's infinite wisdom, those who do not know Him are judged by what they do know. Frankly, I don't know how God is going to work all of this out.
But this I do know.
Apart from Jesus Christ, it is impossible to be "saved" - to receive the salvation of God.
Why not give Him a try? Why not put this objection you have on the "shelf" and investigate the trughs of who He is, how much he loves you and each of us, and find out if He is real or not. He will take care of answering the rest of your questions in time.
Try Jesus - in truth - ask Him to come and touch and transform your life - IF HE IS TRUE - and then thank Him for doing so. You don't have to be emotional. You don't even have to "feel" anything.
Just try Jesus Christ. Then let Him answer your questions.
By the way - if you are concerned about "justice" - for the heathen.
Where is the justice in this?
God sends his Son who though He knew no sin, becomes SIN for us dead Godless sinners - taking the punishment due our SIN on HIM that WE might not come into Judgement - but have eternal life - we who to Jesus have turned for salvation.
How is that JUST?
It is only Just because our God is not only Holy and Righteous and Just - but He is also a God of grace, mercy, and love and LIFE. He (God the Father) willingly suffered the sending of His Son to suffer and die for us. He (God the Son) willingly obeyed His father to come and suffer and die a death most of us cannot even come close to imagining in its horror and humiliation). God the Father raised Jesus the Son from the dead - exalting Him above every name on, below, or above the earth.....BECAUSE He was willing to obey His father and come and die for us who believe!
Frankly - if I had been God - I would probably have just left this stinking earth and its depraved human beings to suffer the judgement they were (I am) (you are) due!
But, thanks be to God, I am not in charge - and neither are you.
The incomparable GIFT to each of us and to this earth corporately is the GIFT of God's Son Jesus Christ! Why not try Him! Give him a sincere try! It is never too late to turn to Him! May the Hound of Heaven who has been seeking you your whole life not stop til you, too, are "caught" and turn to Him. There is nothing to lose (but sin, death, and hell) - and everything (forgiveness and cleansing of your sin, empowerment for life today, and the eternal security of knowing you will be with Him Forever!