I'd say you don't have a clue about who is actually saved and who just claims to be saved. Believers don't live according to the flesh BECAUSE they are not in the flesh, but in the Spirit.
Romans 1 is talking about how man is created with a conscience, when they go against their conscience and sin, they become sinners. People are saved when they obey the Gospel....which means they believe it, trusting the Lord Jesus Christ. When that happens they are indwelt by the Holy Spirit and become God's workmanship. We receive the free gift and have signed on for life.
Now, I've asked you to read this before, but you can't have. Try again to hear what Paul is saying. These are facts...not merely possibilities. When the Spirit of Christ dwells in us, we are given eternal life. He paid the wages of our sin (which is death), and the gift of God is eternal life. Romans 6:23
Romans 8:9-10 But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his. And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness.
You doubt because you refuse to believe what God Himself tells you through His word. You either believe what is written or you make up stuff on your own like God's UNtruth does.