Those who do not profess to public their faith in Christ are considered as "Insiders". These such as Gandhi, and those in this article, inwardly follow Christ from His teachings to even believing His divine lordship, but they do not outwardly call themselves Christians.
The reasons are plenty: Political, fear, etc.
Instead of forcing religion on people, my answer to this confusion is Matthew 20:32. Christ's warning against those who would drag our Lord into their own shyness and cowardice.