Is it possible for one to lose his or her salvation or not?

Is it possible for one to lose his or her salvation or not? I have been seeing some preachers saying once saved, forever saved. What's your insight on this?
Ah, Damilola, you have asked a question so dear to my heart. It's a very good question, a very worthwhile question that is deserving of an answer. I'll start by saying that before we can even ask if salvation can be lost, we have to accurately define what salvation is.
When you say you are saved, the word "saved" is related to safety, right? Where a person takes you out of a place of danger and brings you into a region of safety. When I save you, I save you from armed robbers, I save you from a lion's den, I save you from terrorists, I save you from something. When you talk of salvation, you are talking about saving a person from something.
Now to ask whether salvation can be lost, you have to first understand what you are being saved from in the first place. Jesus spoke to the Pharisees and said to them, "You shall know the truth, and the truth shall set you free."
The word "free" pertains to salvation because salvation means to release someone from the grip of something. And they replied to him, saying, "We are sons of Abraham and have never been in bondage to anyone." And Jesus Christ said, "So long as there is sin in you, you are a slave to sin."
When the name of Jesus Christ was given to Mary by the angel Gabriel, he said, "His name shall be called Jesus, for he will save the people from their sins."
So God doesn't come to save us from our father's house. He doesn't come to save us from traditional religion. He doesn't come to save us from Islam, Buddhism, or Hinduism. He doesn't even come to save us from Christianity. God comes to save us from our sins, from our iniquities, from our shortcomings.
And we have to define them:
Pride, where the spirit of arrogance makes us say things, makes us overestimate ourselves and our value, and makes us feel good only when we put people under our feet. That is an example of a bondage that Jesus Christ saves us from.
What about rage, when our emotions enter into a state of overplus and we don't care who is harmed in the process of us trying to relieve ourselves of a pain we're feeling. That's a bondage that Jesus saves us from.
What about lust, pornography, masturbation, and fornication—these are bondages, right? Where a person cannot help themselves but fall into the bed of someone. That's an example of a bondage that Jesus Christ saves us from.
I can't help but lie. I can't help but steal. I can't help but lose my temper. I can't help but be greedy. I can't help; I can't help. Something has held me bound, and that's what Christ enters to set us free from.
So if your bondage was lying and Christ delivered you from lying and whatever made you lie, and you have tasted the freedom of being one who can tell the truth without fear of anything, and then next week you go back into that realm of lying again, you go back into that realm of stealing again, you go back into that realm of fornication again, question for you: Are you still safe?
Remove the word "saved" now because that semantics can confuse, but look at it: are you still safe? There was a person that was crippled that Jesus Christ healed, and he told him, "Go and sin no more, lest something worse may befall you."
Why did he say that? This is Jesus Christ himself. This is not even one of the apostles who performed the healing on the person. And he let him know, "Your healing is not permanent; your healing is contingent upon the decisions you make from this very day. And it's possible, even though I have set you free, that with your own hands you can enter into bondage again."
So therefore, Paul says in the book of Romans, chapter 5, "Do you not know that you are slaves to whomever you obey? Whether it's God leading to life or whether it's sin leading to death, so whoever you obey, you are a slave to." And in this world that God has created, no one can live life without being a slave to something. You are either a slave to Jesus or you are a slave to the spirit of this world.
Now Christ can come and deliver you from the clutches of the spirit of this world, but if you go back and obey something that Christ sets you free from, friend, bondage has come again. It's a very big teaching, but that's just the general summary that I believe even a layman cannot deny, no matter how much scripture you want to quote.
Praise the Lord! I hope this helps you, my friend. God bless you.