Wrong. Learn what that Scripture REALLY means:
Hebrews 13:4-6 - Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers, God will judge. Let your conduct be without covetousness; be content with such things as you have. For He Himself has said, "I will never leave you nor forsake you." So we may boldly say: "The Lord is my helper; I will not fear. What can man do to me?" ~ Note: That does not mean you can go out and be a fornicaor, adulterer, or a coveter and not fear that God will never leave you. The key is to be content with what you are, being not in sin, then God won't leave you. If "Once Saved, Always Saved" was true, then there would be no point of the warning "God will judge" in 13:4. You can't take the quote, "I will never leave you nor forsake you" out of context. That's what people do when they try to think that this means eternal security. Also look at the next verse, 13:6 is quoted above, it applies to this "never leave you" quote with the word so. So it is connected. "The LORD is my helper", not the covetousness (loving money). So if you keep obeying God and listening to His warnings, then He won't leave you, but if you start the practice of sin, He will leave you and you will need to repent again. It states, For He Himself has said. Knowing where it comes from has some important points to know. The Lord spoke to Joshua, "I will not leave you nor forsake you" (Joshua 1:5). Before that, "He will not leave you nor forsake you" is what Moses told the people and then Moses told it to Joshua (Deut. 31:6,8). The reason Moses said this is because he just told the people that the Lord told him that he would not cross over the Jordan. Moses was giving them assurance of their crossing without him. It doesn't mean that we can do whatever we want (like being a fornicator, adulterer, or coveter), and God will never leave us.
In fact, after this word was given through Moses to the people, the Lord said this in Deut. 31:16,17 - "Behold, you will rest with your fathers; and this people will rise and play the harlot with the gods of the foreigners of the land, where they go to be among them, and they will forsake Me and break My covenant which I have made with them. Then My anger shall be aroused against them in that day, and I will forsake them, and I will hide My face from them, and they shall be devoured." ~ Note: We see that God said that He would forsake them because of their sin. So people should not be preaching that God will never leave you nor forsake you no matter what you do, because we just saw the truth of God saying otherwise. I see the Lord corrected in what the people there and the OSASers now may have thought the "never leave you" to mean, because what the Lord said about the people is different than what Moses said. But Moses was referring to God being with them without Moses crossing with them, not God not forsaking the sinners. So if you been telling people that God will never leave you nor forsake you, maybe God through Scripture (Deut. 31:16,17) is correcting you like He did then. True, it's in Hebrews 13:5, but if you take it out of context by not mentioning the verse before and after it, then you could be preaching the license to sin.