If you follow Jesus Christ you WILL stay on the straight and narrow path. YOU WILL NOT SIN because you will be focused on Jesus all the time and you will seek His approval, you will seek to be pleasing to Him all the time. You will be going after the kingdom of God, doing those things that Jesus guides you to do. You will FORSAKE your own thoughts, your own ambitions, your own plans and you will do as Jesus guides you by His Spirit that lives in you.
It does not mean that you will not stumble because it is human to stumble but YOU WILL NOT WILLFULLY SIN. Jesus does not excuse willful sin. If we willfully sin we rebel against God. Adam disobeyed God ONCE and he perished, he died. God said to him:”The day that you eat of that tree you will die” and he died. Spiritually he died because he was separated from God, physically he only died many years later but HE DIED.
The wages of sin is death. The moment you sin against God, the moment you disobey Jesus YOU ARE SEPARATED FROM HIM because you are in rebellion against Him. If you stumble, if you sin unknowingly He will convict you and pick you up but if you WILLFULLY SIN He will PUNISH you, He will DISCIPLINE you. If you refuse to OBEY Him, if you refuse to REPENT and STOP DOING that WRONG action you will perish, He will CUT YOU OFF!
Many believers live in fornication, they willfully sin, they love the world and they say you cannot stop sinning. They are not following Jesus, they are following the lusts of their flesh and they will be cut off, they will perish, they will end up in hell.
If you want eternal life you have to BE HOLY and BE RIGHTEOUS and BE CAREFUL that you do not fall into temptation. Jesus said:”WATCH AND PRAY that you do not fall into temptation.” If you stay focused on Jesus all the time YOU WILL NOT SIN, you might stumble and He will pick you up but you WILL NOT SIN. Sinners will not enter the Kingdom of God, they WILL perish in hell.
May Jesus bless you.