The purpose of Vinaya is to train oneself to abandon defilements. If used
skilfully it is an excellent tool for training oneself in renunciation.
Even a lay person can derive benefit from studying it for this purpose.
However, all of the sectarian divisions and disputes have arisen over
different interpretations of the Vinaya, with each sect doing their utmost
to discredit the other. One should bear in mind the simile of the snake in
the Alagaduuppama Sutta.
"Here, monks, some misguided men learn the Dhamma, but they do not examine
the meaning properly. They learn the Dhamma only for the sake of
criticising others and for winning debates. Those teachings, being wrongly
grasped, conduce to their harm and suffering for a long time. If a man
needs a snake he should catch it with a cleft stick and pick it up behind
the head."
In the beginning there was no Mahaayaana or Theravaada. There was only one
Dhamma-Vinaya taught by the Buddha. The right way to study Vinaya is by
practising it as a bhikkhu, and living it day by day. It is a gradual
training, and not something one can perfect until one gains Arahantship.