To some people, the exclusive nature of Christianity is so repugnant, they use it as an excuse not to convert. A simple question for those people: Is Christianity true?
If Christianity was not true, there would be significantly better reasons to disbelieve than "it's too exclusive". Truth, by its very nature, is exclusive, so it's a feeble excuse no matter which way you cut the cake. Thus, if Christianity is not true, there must be better arguments.
But what if Christianity is true? What if there really is a Heaven, and a Hell, and only one way to receive the former? In this case, rather than exclusivity being an excuse to reject it, exclusivity is a great reason to accept it. If the idea of so many people going to Hell is so repugnant to you, why would you risk going there? Furthermore, why would you deny anyone else the right to receive the Gospel through you? If Christianity is true, the people you say God should let into Heaven are still on the path to Hell. But you know the Gospel. You know that God literally sent Jesus to pay the penalty for their sins, and all they have to do is repent and believe and they, too, can go to Heaven, yet you, out of sheer selfishness, not only reject that same gift for yourself, but also impede their reception of it.
God, in His infinite justice and sovereignty, owes eternal life to exactly zero people. We're talking about the God who literally made the entire universe. The ground beneath your feet, the stars above your head, the food in your cupboards, the water in our oceans, the very materials which we use to create our own creations, even our own kind, everything under Heaven belongs to God. That makes you the equivalent of a paper plane compared to God. He looks at us and sees grasshoppers. Do you mourn when you step on an ant? When you swat at a fly? Even PETA and the RSPCA are known for killing animals, seemingly without remorse. And how few people oppose even abortion? That "clump of cells" whose arms and legs are torn off by so-called "doctors", is of infinite worth, and yet so many people consider abortion as anything from the lesser of two evils to something worthy of celebration.
So what should God care for us? He made us, therefore He owns us. We rebel against Him, therefore we're not even at the level of fully functioning creations. We are made in His image, yet we are so stained with sin that only He can restore us. And we reject that restoration, right to the bitter end. We act like He owes us eternal life, complaining when He doesn't give it to us, and yet when He pays the ultimate price to give it to us for free, we continue to reject it, because we don't even really want it! We are like fat people who want to be slim, while we eat like pigs and never lift a finger. We are like poor people who want to be millionaires while gambling money we don't have, expecting the casino to pay us every time we inevitably lose. We are drug addicts who say we want to be healthy, yet spit in the face of every doctor who seeks to help us recover. Foolishness! It is foolishness beyond belief to spit at the God who offers, free of charge, that which we seek from Him. If you really care so much about the exclusive nature of Christianity, put your money where your mouth is. Get saved, then seek to save others too.