The atheists are so lost.
The big picture is, it's shown in the story of Eden that Adem fell due to 1) lack of faith in God, and 2) lack obedience. Obedience is assessed by means of Law, which humans are doomed to fail. Faith is required by humans to live with God because relatively humans are made to be with low ability and low intelligent. They don't fully understand God's creation, such as why the 2 Trees in the garden of Eden. That's why we need faith in God as we lack the ability to fully understand the design and purposes of God's creations. Angels on the other hand, are creatures of high ability and high intelligence as their very existence is to participate in God's works of various creations, perhaps that's why the fallen angels are specialized in exploiting God's creations.
If by the judgment of Law one is dead, there wouldn't be forgiveness. Forgiveness is a grace outside of Law, it belongs the scope of covenants and only applicable to humans. To simply put, forgiveness doesn't belong to Law but as a grace which can only be found in covenants, while covenants are only applicable to humans. Good deeds are also a comparison against Law. A good deed is a work of Law, and subsequently a reflection of one's obedience (i.e., you choose to do what Law defines as good). Accepting forgiveness or repenting belongs to the scope of covenant and grace, instead of Law. It won't be considered as a "work of Law". To put it another way, repentance as a pre-requisite for forgiveness belongs to faith (grace) instead of Law/good deeds. Conceptually speaking, there's no forgiveness granted if one refuses to repent.
Our salvation is already the "best way", or else you may ask atheists to offer a way they think that it is better. There's no better way out there. The core of salvation is basiscally a faith in the testimony of human kind about God. God has a direct contact with His chosen eyewitnesses and for them to write down a testimony for the rest of human kind to believe with faith. That's the core of salvation. Humans on the other hand are with low capability and low intelligence, a testimony is valid when it's made the best human capability and effort. There's no anther human book is with better human effort and resources put forward. It's already the best humans (basically the Jews for OT and Christians for NT) can do, and is conveyed in the best human way. In the end, it's a human account of testimony and not a God's account of testimony. It's validity is finally determined by the court of Heaven on the Judgment Day. To make is simpler for the atheists, if they think that the Bible is not the best, they can provide a human history book written 2000 ago which can be deemed better in terms of human effort and capability, especially from a comparable ethnicity as small and unimportant as Israel.
As for the number of humans saved, it's mathematical. It follows mathematical laws to work. God won't work against mathematical laws for "more humans" to be saved. The atheists better learn what Statistics and Probabilites is, especially on what Expected Outcome and Normal Distribution are. The mathematical expected outcome with the assumption of a normal distribution will point to a salvation through the narrow gate! "Wishing all be saved" represents a shear probability in terms of a human behavior distribution. God speaks in mathematics when it is said that "humans are saved through the narrow gate" and "wish all humans are saved"!