Is it a good idea to force stop apps after using them? I find myself using force stop for every application once I have finished using them. Is this a good practice? Are there any performance or security benefits of doing this? Is force stopping an app necessary to get it out of RAM?
TL;DR:

No, it's not a good or advisable idea.

Explanation and some background:

Force-stopping apps is not intended for "routine use", but for "emergency purposes" (eg. if an app runs out of control and cannot be stopped otherwise, or if an issue causes you to clear cache and delete data from a misbehaving app). Generally spoken, it's neither a "performance booster" nor a "RAM optimizer".

In many cases it won't save battery life either, but rather deplete the battery even faster. Apps don't only start when you tap their icon, they can also get started via intents or broadcasts (eg. on battery low, network changed, USB device connected – but also on many more). So when you "force-stopped" it, on its next start it will have to do a "full init" (loading from the storage(s) and the network) instead of just going back to its "last state" still stored in RAM (unless the system had to clear it out – see our oom-priority tag-wiki for details on that process) – what Andy described as "will increase loading power consumption / time" in his comment on your question.