Saints and Pirs are sent by God to perform a particular task in this world. AjmerSharif Baba was sent to spread Sufism, Saibaba was sent to bring unity between Hindu and Muslims, Sant Kabir was sent to compose religious songs which can be sung by people from all religions and there are innumerable such examples.
Similarly India, Pakistan and Bangladesh all were under the British rule and people were suffering. To relieve the sufferings of people and get them freedom from foreigner's rule, Gandhiji aka Bapu was chosen by God and sent to this world to carry out this task. He used the well-known time tested path to achieve independence, that is, Ahimsa which is the basic principle of all religions. Ahimsa does not limit only to "not killing" but also extends to "non- retaliation to any provocation" Only a saint can remain calm and composed instead of all the turmoils and wrong-doings from others and though Gandhiji lived the life of a Grihashtha, he was no less than a saint - a Karmayogi Saint.
Gandhiji said - " An eye for an eye makes the whole world blind". Only a saint with his divine power and energy can drive millions of people to follow a novel path to achieve Independence. During freedom fight, millions followed him blindly and sacrificed everything. Ultimately with the people's support and strength He got Independence for them....so silmilar to the incidence where Moses asked his followers to cross the sea and they followed him blindly and even sea parted to make way for them to reach safe land beyond the reach of enemies.
When saints work is over they usually leave the world before getting entangled in worldly matters. Probably when Almighty realised that Bapu's work was over, he took him away.
He was a true Karmayogi Saint because he practised as a Lawyer after obtaining Law Degree from London, married and had a family, lived a life of Grihastha but donned the qualities of a Saint and worked unstoppingly to get Independence for all of us!
He is indoubtedly a true messenger of God who brought solace to millions of people in Indian subcontinent without a single weapon or ill spoken word against the all-powerful British Raj. His principle has been followed by the most advanced country in this world - USA - Martin Luther King!