I’ll make a case that even if Jesus is God, it’s irrational that this belief is necessary for salvation.
The name Jesus refers primarily to Jesus the man, but we cannot have a relationship with Jesus the man because he is no longer here. God came to Earth in the form of Jesus to atone for man’s sins, offer salvation, and draw man into a closer relationship. Jesus was fully man and fully God; let’s call these two counterparts Jesus the man and Jesus the God. Without the man, the name Jesus would not be associated with God. God was not previously called Jesus. God chose to come down for a time and interact in human form, and that human form was named Jesus. The name Jesus refers primarily to Jesus the man. While Jesus lived, his followers had a relationship with both Jesus the man and Jesus the God. After Jesus the man left the Earth, Jesus the God remained. Those who were born later don’t get to meet Jesus the man, but we get to meet Jesus the God. Our relationship with Jesus is devoid of fleshly interaction, as opposed to our human relationships which depend largely on the flesh (which is why we’re devastated when loved ones die). When we say we love Jesus, we cannot be talking about Jesus’ flesh, Jesus the man. We don’t love that cute mole on his cheek, that funny look he gives us, his bright demeanor, his skills as a carpenter, his generosity in building mom that beautiful cabinet, or his charming table talk. We can’t know Jesus the man, so salvation wouldn’t be related to that (or else we are all doomed). Salvation can only be related to a relationship with Jesus the God. But Jesus the God is simply God, the same God that existed before Jesus lived, infinite and good (This is where lengthy Trinitarian arguments would enter, but in short I fail to see how Jesus the God is different than God without entering polytheism).
My point thus far: a relationship with Jesus the man is impossible, and a relationship with Jesus the God is simply a relationship with God, since God is One. It seems that if someone has a relationship with God, then they have a relationship with Jesus the God whether they know/believe it or not. But the fundamental Christian doctrine is not that one must have a relationship with God, it’s that one must believe that God acted in history in a particular way; that God came to Earth as Jesus the man to save us. That’s really the crux of Christianity, “believe this story.” Everything else, like loving God and being a good person, is secondary to believing the right story, and seen as “Satan masquerading as an angel of light” in the absence of the right story. Christianity is all about the right story. Just “believe (this story) and ye shall receive.”
I’ve found the question of Jesus’ deity to be an academic exercise of analyzing questionable ancient writings and weighing through 2000 years of debate and controversy. It is impossible for mankind to reach a unanimous decision on Jesus’ deity, the evidence is too controversial and the truth is lost in time. Why would God make salvation dependent on figuring out this impossible question? Why, of all things, would the most important thing in God’s eyes be that we believe a particular story? Why would God value this over love and good character, character that has matured into his image? If God chose to save us through Jesus death, then that’s wonderful for us, but why would God only save us if we believe the right story about how he did it, not have Jesus write a word of the story himself, leave the story to be written by unknown authors at unknown dates after years of being passed verbally, allow multiple discrepant versions of the story into mainstream circulation, allow clear instances of the authors' theological preferences and legendary apologetic embellishments into the story, allow later additions to the story to become cemented in, leave the story all-around mired in controversy, and leave mankind incapable of little better than chaotic disagreement on the subject?
This view of salvation seems irrational to me, and seems to have the signature of man all over it. It looks like something man made up, not God. It would result in gross failure of God’s will that all be saved. It would not be good news for all people. Father’s do not expect their children to understand a dangerous situation before they save them from it. A patient receiving a heart transplant may have no idea who performed the surgery or how the surgery was done, but the doctor doesn’t expect him to know and the success of the surgery does not depend on him knowing.