Belief in one God, that Prophet Mohammad was the last messenger, in his angels, his books and in paying zakat and doing the pilgrimage if financially able.
It is doing 5 prayers a day and paying sadakah to the poor.
Anythng above that is Sufism.
So If you have accomplished the minimum required in Islam and you want to be even closer to Allah, we are showing the gateways.
Are you required to be a Sufi to be loved by Allah, absolutely not, you are merely preparing for your next life.