I think that "at this point" and "at this stage" are pretty much interchangeable, however I perceive that there might be a slight difference. I have been looking into the internet and have not found anything clear enough. Can anyone offer a substantial clarification about this topic? In addition to this, I am also interested in getting to understand the difference between "at this point" and "in this point". So I would also appreciate any resource or explanation in respect to this.
The two are very similar but I can give you a feel for the slight difference in connotation.
"At this point" implies that there is a continuous process going on. We stopped at 87.34% but we could have stopped at 87.35% and circumstances might be a little different.
"At this stage" implies that were are a few discrete phases where we could have stopped. We are in stage 3 of 5. If we wait a few more seconds, we are still in stage 3 and nothing has changed. It also might imply that something noteworthy changed in our circumstances between stage 2 and stage 3.
"In this point" is quite a different phrase, and is not common and generally used like the other two are. The example I can think of is if I was referring to points as objects that contain things. For example, if I was going through a presentation slide and in the third bullet point I say something interesting.