Once saved always saved is not the same as the perseverance of the saints that a Calvanist would believe.I told you what Calvanism was because you believe one of the things that Calvanists believe... which is Perseverance of the Saints (once saved, always saved)
The Once saved always saved version of Calvanisim adds a work to salvation which is that if you dont have the works to show your faith then you are not saved or its not a true saving faith.
The problem with that thinking is that we don't have to have any works to show we are saved and yes a carnal christian can go live whatever lifestyle they wish and still be saved if and only if they are trusting in the Death, Burial and Resurrection.
So yes Calvanisim, like any other false religion or false gospel out there, will take some truth or look like they have some truth, but they will spin it and turn it into a works based religion by either slightly changing or blatantly changing it.
So yes, Perseverance of the Saints (Once Saved Always Saved) is a Biblical Doctrine. But Perseverance of the Saints in the sense that you must have works for it to be a true saving faith is a works based false gospel.
I do apologize if, you were just trying to point that out and thought I was a Calvanists.....Its the problem with discussing these things via internet as opposed to face to face you miss the body language of the person you are conversing with.