Hmmm... A question for the ages. I cannot answer definitively for anyone but myself. Christ tells us through the epistles to "work out our salvation with fear and trembling". However, to me, who is a simple woman and mother, I have to think about the prodigal son.
You know, he was the young man who wanted his inheritance NOW. He couldn't wait until dear old dad died to get it. He was kind of like the little boy who kept asking his grandpa to make the frog sound. Upon being asked why, the little boy replied that his mom had told him that as soon as Grandpa croaked they would go to Disney World.
Our impatient young man got what he desired. Dad gave him his inheritance. Please keep in the back of your mind the "good" son. The impatient fellow left town! Man he partied like there was no tomorrow. He had friends going and coming. He partied until the inheritance money ran out. The friends ran out too. I guess you could call them fair weather friends. That's another story worth exploring one day.
Our poor young man was out of money and friends. Whatever was he to do? He got a job feeding hogs. Now hogs were nasty to our Jewish friends of the day. But since a famine had happened this most inopportune time, he just about had no choice but to take what work he could get. But guess how he ate? Yep, he took the hogs slop and ate it. YUCK! He decided that since he had disowned his family by dishonoring his father the way he did that his dad would no longer consider him a son. He had thrown away his sonhood by deserting his family and taking money that could have been used to increase the family fortune. He did have one recourse. He could go back home where there was food and shelter and become a servant. He knew the servants had food and shelter at his family home.
I guess this young man was smart. He was just foolish and learned the hard way that his life was not so bad back in Dad Land as he originally thought. So, he girded up his loins ( I love the picture that phrase connotes) and went back home intending to ask for a job and live in the servants quarters.
Dad saw him coming. I wonder each time I think of this parable if the dad made a habit of looking up the road for his boy. I'll bet he did. Dad met him and hugged his son who was lost and now found! Note that before the young man was able to say a word the dad embraced him. He called for the best robe, a ring, and shoes to be put on his son, his baby, the fruit of his loins. He ordered a party too! The fatted calf was cooked and they ate and had a party to celebrate the homecoming. I can only imagine how he felt.
Now the "good" son, the one who never denied the father and stayed there was MAD! He came up to see what was going on and found his sorry brother who was a ner do well getting the royal treatment. He called his father out on the father's foolish decision. He was jealous too. He asked his dad why he never got a party since he was so perfect. Here is the crux of why I believe in once saved always saved; the father told the son that the other son was lost or dead for a time and now he was back. He never said anything about the sorry son not being a part of the family. He always was whether or not the son would admit to it.
Now the mother part: my children carry my blood and genes inside them. I don't care how much they deny their father or me they will always be my children. I will always be their mother. So, in my mind, considering the parable of the prodigal son and my own experiences how can I ever think that I could lose my salvation. I am God's child because I asked Him into my heart and confessed Him with my mouth, according to Romans 10:10. He is my Father and I am His child, no matter what.