I know you’re a firm believer in OSAS. I had an uncle who preached the gospel in his church, led many to God over the years, had a great testimony in the church and community. Somewhere along the way, he fell into a grievous sexual sin. He got found out, left the church, walked away from God. He made fun of those who continued to follow God. Are you telling me that he was saved and when he died he went to heaven?
It’s not for me to say if your uncle was saved or not. But in two different places, Paul said a believer’s inheritance is guaranteed. In Ephesians 1:13-14 he said the guarantee takes effect the moment we believe. In 2 Cor. 1:21-22 he said God anoints us, sets His seal of ownership on us and puts His spirit in our hearts as a deposit, guaranteeing what is to come. In Colossians 2:13-14 he said Jesus forgave all our sins at the cross. That means each and every one of them.
Jesus promised not to lose any of those that God has given to Him (John 6:39-40) and He said no one can take us out of His or His Father’s hands (John 10:27-30). In Romans 8:38-39 Paul confirmed that means no one in heaven or on Earth. So, if you see your uncle in Heaven you’ll know he was always saved, and if you don’t, you’ll know he never was.