Here's the critical part. Let's get it out the way first. Some, perhaps many, confer upon his majesty a sense of infallibility. Catholics did this with the Pope just as Christians did with Jesus. It may be parts of their stories are always edited in order to play to this perfect narrative. A side effect of this is that if one of these people said something, not objectively true, it is assumed to be true because they said it, by virtue of their stellar credibility. Saying, they were wrong about that can be very uncomfortable, because as humans... we seek perfection.
In the second paragraph Selassie says "there is no perfection in humanity. From time to time we make mistakes." He says we which shows that he includes himself. This is important to keep in mind; that he was fallible.
He starts off saying "when Jesus Christ was born from virgin Mary"...
Mary wasn't a virgin. In this same effort to seek perfection, Catholics seized on this word that was translated to virgin. And they took it literally and assumed that it must mean that the birth of Jesus was a miracle, and that, like Anakin Skywalker, his literal father must have been God because he had no earthly father because his mother was a virgin. The problem is that the word simply pointed to Mary being a young woman. In the prophecy of the virgin birth in the Old Testament, it was fulfilled by the prophet's young wife. The point is, we change the story in order to fit our conception of divinity. We want it to be true so badly that we often ignore facts and evidence to the contrary. And eventually we start selling that narrative and it gets passed from generation to generation without us going back, skeptical, and using critical thinking to correct those mistakes.
Now for the good.
Haile Selassie I, from what I can tell, was a devout Christian because he was following an idea, not a man. The man was just an embodiment or an exemplar, of the idea that was of to great interest and influence to Haile Selassie I. He says, " He lived an exemplary life, a life which men everywhere must emulate."
And again, when he says everyone, he includes himself. From this I can discern that he followed Jesus "in spirit". He also wanted to embody that same idea. And it wasn't, for him, about some heavenly paradise, but "good life upon earth" as he stated. "this healthy life" which for him, was a Christian life.
Some will advocate for Christianity just because his majesty said this. However, I don't believe Christianity was the literal idea. It was, for him, because it was the vehicle through which that idea was expressed and taught to him. But we can see that the idea within the vehicle of "Christian Life" is what "makes me follow Jesus Christ" to quote Haile Selassie I.
Does that mean a Rasta should be a Christian? No. It means that a Rasta should embody the same idea that Selassie believed "Christian Life" also embodied, that same idea that Jesus embodied. What is this idea? For H.I.M it was faith and love. Of course he didn't stop there. He included biblical teaching. Why? Because, in his mind, that is what was best for the nation to treat each other a certain way so that we could live together in harmony as he eluded to previously.
I wish I could reason with him and push back on this notion because although the bible promoted harmony within their own nation, they often fought with other nations. And this eventually leads to a Babylon type of state. Yes, everyone thinks fighting is good when they're winning. But what happens when you lose? I'll save that topic for later, but as a king, Selassie had to defend his people, even against other Christians. But I think he wanted peace and harmony and that's why he said he was also king over Muslims and others so that there could be harmony between people of different faiths, rather than trying to force everyone into one. That wasn't his way. It was love.
"He taught us that all men are equal regardless of sex, their national origin and tribe." - H.I.M
I think this also covers religions because religion was often just a cultural offshoot of national origin and their way of thinking and governing. When different cultures run into each other their variant systems of spirituality and their underlining myths and legends do as well. These myths and legends aren't simply stories. Fact or fiction, they are sources of guidance and inspiration. And so they become holy and sacred to those societies. Often people fight against these others because they're afraid their own culture and traditions will be lost.
But what we were taught in the bible was both good and evil, just like every other kindred and tongue. Even though Selassie just said that women were equal, "regardless of sex", the bible made it clear that they weren't and were subordinate to men. This was an old way of thinking. And instead of thinking that Selassie just didn't know... I think he did know but didn't care because he understood that was the past. And that was the thinking of the past. Unlike Moses, Selassie had 1 wife. And she was kind of a precursor to someone like Oprah.
So I don't get a sense that Selassie was stuck on the bible or even was, for that manner, a biblical scholar.
"I would also advise him to seek the secular knowledge, for the more one knows the more he realises the need for a prime mover, the need for a Creator, a Creator who is good, and the need for salvation and also for peaceful life upon earth." - H.I.M
This tells me a lot. It tells me he had a more "Intelligent Design" theory; speaking of "a" Creator, not necessarily prioritizing "the" Creator who was of a certain creation story, type, etc. Just "a" creator. And then he infers goodness upon this creative role based on his observation of the overall good in creation. Again, I wish I could reason with him because I feel the same; however, one has to note the amount of death and consumption of life that ultimately gives way to more life. So many animals eat other animals and we eat them. And even if there are tons of animals who are vegetarian, vegetation itself feeds on the dead bodies of both plants and animals. And without that fertilizer... would the land be "fertile"? And would those plants be able to grow there? For me, the prime mover is "the Force"...(yes, like in Star Wars) ...it is Energy. There's no magic. If there was magic involved then the circle of life wouldn't require death. Instead, we are one of the many forms that Energy takes. But again... Selassie keeps coming back to the idea of a "peaceful life upon earth". This is also what I seek so I believe we would have gotten along.
"if we dedicate ourselves to this fundamental task, then we will have a peaceful world"
The interview goes on, but in the last paragraph I quoted in the OP, Selassie is addressing new Christians, not anyone else. So this isn't him telling others to be Christians. This is him telling Christians how to be Christians. Again, his intended purpose is revealed, as mentioned several times, "a peaceful world".
So again, I say, it's not about Christianity. Selassie's religion was "incidental". He could have been a Muslim. He could have been a Jew. He could have been Hindu or Buddhist. These words don't matter because it was the ideas that spoke to him and inspired him. He wanted to be a good man. Many follow Christ in order to get rewards in heaven; to get eternal life. I sometimes say that I'm a better Christian than most Christians because I still, even after giving up Christianity and Judeo-Christianity as a whole, still emulate the character and nature of Christ and now too the character and nature of Haile Selassie I. And I believe in both cases these were men with divine ideas and influence and inspiration and power and love. And we should all be Christians in THAT sense. And we should all be Rastafarians in that sense if nothing else. But we have to embody Selassie's desire for harmony and a peaceful world.