I disagree,

A follower of Jesus is the one who observes everything He taught them (Matthew 28:19-20). His teaching was not restricted to the golden rule, He spent alot of His time talking about His kingdom and His very first message in Matthew 4 was for people to repeat and believe the gospel.

A follower of Jesus is one who repents and believes the gospel, i.e. places their faith in Christ's death for sin on the cross and His resurrection for their justification.

Following the principles of Christ is fantastic but it is faith in Christ that saves. Hence Christ rebuked the Pharisees for searching the scriptures and thinking they could find life in that while refusing to come to Him, who the scriptures point to that He might give them life.