Rouxne van der Walt,
Well, just as there are positive and negative people, I believe that there are positive and negative non-physical entities. If you read Erin's blog, she's run into quite a few of them! (It makes for entertaining reading.
I cannot convince you either way, but I can explain my own beliefs. I believe we are here for our own soul to grow as much as possible, which cannot happen in one lifetime. Therefore, I believe we return to the spiritual realm between lifetimes to review our last life, and to prepare for the next.
I believe that there are different levels to the spiritual world. As you get higher, (higher being a relative term, higher in vibration I should say), the entities become more positive. The negative entities hang around the lower realms, close to the physical, because they can't go any higher. Who they are, I don't know. I don't know if they ever have or will take physical form, or if they are just some sort of weird non-physical negative entity. Maybe they are even just manifestations of people's fears. Either way, I am sure that they exist.
I don't believe in hell or a devil, either, and I'm not saying there is any sort of torture or anything in these lower spiritual realms. Just that there are different vibrations, and the lower ones attract negative entities, who cannot go any higher. That is why people who have died sometimes are stuck around the physical for a while, because they are hanging onto some issue or they feel guilt, fear, etc, and so can't move higher.
As for returning to source, yes that may eventually happen. But I don't think that it happens for each person immediately after they die. I even think I may subscribe to eastern philosophies that say you must reach enlightenment before ending the cycle of reincarnation.
I would like to point out that you are using the term loving. that is of course common, but note that in this dualistic world, everything has its opposite, and therefore no adjective can really be used to describe that source we are discussing. If something is loving, there must also be something that is hateful. This, then, is not source. Only when you abolish all duality can you find source.