Yeah - those who opt not to accept Jesus as their Lord and Savior are doomed. What mortal can decide that one who has accepted Him has not done it to their standards and will therefore be denied the Kingdom of Heaven? He knows our hearts and other mortals can only guess - if you got a new priest who decided that the lot of you were going to Hell, would you listen to him or rely on your personal relationship with Jesus?
Luke 10 is aimed at those who refuse the message of Christ - He tells them to carry the extra message but He doesn't give them authority to send folks to Hell, it is His authority used to send the message.Also, He was still living in the Old Covenant and had not shed His blood that the sins of others might be washed away if they decided to accept Him.