Why do you think that God would want it to be difficult or a long process to believe in him? Because clearly not everyone is ending up believing what you believe, so clearly the method God have chosen doesn't really seem to work, wouldn't you agree? Because evidently a whole lot of people end up with the wrong religions?
Its not a matter of you not wanting to "interfere" with others beliefs, you unwillingly claim that they are wrong. Don't misunderstand me as trying to point you out, because atheists do this all the time against all religions, unwillingly our claim is that we don't believe that any God(s) exist and therefore we don't see any reason to believe that any religions are true either. Equally as any person that follows a different religion than yours, they also unwillingly claim that you are wrong, for the very same reason as atheists do. But maybe atheists are just more open about it, I don't know.
The big difference is, that as an atheist, I can easily say that I don't mind what someone believe, because I don't think any of them are true. But that doesn't really apply to you in the same way, because you do believe that a God exists, and that its the one you believe in. So the question, becomes relevant for you, of why you think that God chose such a complicated way for people to end up believing in him, because it clearly doesn't work, if God's intention is for humans to believe in him as a Sufi? Do you see why that is kind of weird?
The belief is only the beginning
After belief comes faith, then more and more wisdom arises about how to get back to God. It has to be difficult for humans because (in my understanding) if we are to become a part of heaven, we have to shred every human aspect (ego) before entering heaven. And that is very difficult to do, a belief is not enough, it is an inward full-time job to understand our own being, faults, egos, attachments, and so on. This is my understanding is why it takes time to enter heaven, and I can't say I am certain to enter heaven myself.
If others claim my belief is wrong, let them do so
I have no wish to deny them their right to believe in something else. And I do not say other religions are wrong. I am very open toward other religions. (mainstream Islam would disagree with me I know)
I do not take your or others view of me and the belief I hold as a negative thing anymore
It is sometimes a challenge, that is true, But it is also at that moment I learn more about my own being and my belief and faith.
I can not claim to know all about why atheists disagree with many religious people, but one thing maybe that different people within the same religious faith, can give you do different answers to the same question.
I think one of the reasons being that people are at different levels of their faith and that by this they do see the truth differently. And when an atheist reads or hears people saying the different answers to one question, it may be confusing to them?
You would probably be able to answer that last part for me