Romans 10:1-2 - Many people believe in God (in His existence). Even Satan believes in God (as do his followers - James 2:19). Many people who believe in God are still lost (Galatians 3:26 and John 8:1-2 and John 8:24).
Romans 10:3-4 - Many people think they can merit Eternal Life by being religious and pious. But all of our very best works are but refuse to Almighty God (Isaiah 64:6 and Romans 3:10-12). We must get the religious to see that their religion has no value at all to God and actually hinders our Salvation (Philippians 3:4-9).