Modern Christianity is a composite of many things, the main being connected to the merger of Christianity with Rome in the 4th century AD. Rome made Christianity its official religion and then tailored Christianity to the needs of the empire. Rome added pagan holidays, to the new church calendar, to integrate the church with the diversity in the empire. Rome was not the official secular of Christianity, since Christianity had been more of slave, underdog. The church was rebuilt by Rome.
The merger had many advantages for early Christians, because it brought protection, scholarship, science, art, multiculturalism, government to the church. The Pope and the Cardinals were like emperor and the senate of Rome. On the negative side, Rome was a world superpower with a tough military tradition. This also became part of the Catholic Church tradition. As Rome faded it away, in the dark ages, it never really died, but was reincarnated as the Catholic Church.
The split up of the Catholic Church, which started in the 15th century, was like cell division, where the 1000 year old fertilized ovum, began to split back into Rome and Christianity cells, of various proportions, to form the cells of a new growing body.
There are now a wide range of Roman-Christians cells, each with different character. These range from Romanist atheists who remained bound to Christianity, through the ties of resentment; mirror. There is also the pure Christian with the charisma of inner faith. There are also those in the middle, some that retain the hard line of Rome in their faith; fire and brimstone, and others with their inner dove of love.
The Christian cross symbolizes the four orientations of perception. The head is intuition/faith, the feet are instinct, the left hand is emotion and the right hand is intellect. The Church body is spread over this cross. Being nailed to the cross is implicit of being in a state of suspension; organic flux, between the needs of the polarizing composite; render onto Caesar what is Caesar's and render onto God what is Gods (separation of church and state).