It seems possible, and perhaps likely, that Jesus Christ's work was at a cosmic and creational level primarily and essentially.
Jesus changed reality, and set-up a new possibility.
The religion of Christianity would therefore be something secondary and optional - a means to the end of being A Christian, that might well be or become an obstacle or deterrent to achieving that end.
If Secret Christians are indeed, and by intent, the main thing; then this is not really "a religion"; because, by usual definitions and practices, a religion is a social-level phenomenon.
Christianity certainly can exist at a social level - but if that reality is love based, then it will be rooted in family and close personal relationships; therefore not in institutional forms; and its reality will not be well represented by such categorical and formal structures as rules and laws.
Thus... Maybe the original assumption of Jesus was that Christianity would be a secret doctrine - "secret" in the sense of potentially private and personal, hence invisible to external perception.
A doctrine so simple that it could be known by direct personal revelation (communicated by the divinity directly to the hearts of Men); and which could be inferred sufficiently just from innate knowledge and attitudes, and common sense reasoning.
It is even possible that such a secret form of being-a-Christian would work best when unspoken and generally uncommunicated -- perhaps being kept separate-from (and unconfused by) religion, reduces the chance of distortion?
After all; the main-thing about being a Christian is Heaven, which is not of this world.
To be born again in resurrection happens on the other side of death.
Following Jesus during this mortal life is bound-up with contingencies; but what absolutely defines our destiny is whether or not we follow Jesus after we have died biologically.
Whether we are Secret Christians or not; the essence of the matter is outwith public discourse - between our-selves and the living Jesus Christ.
