Unlike popular belief sikhs do not believe every religion leads to Vaheguru but only one way. Gurus said only way of liberation or getting 'mukti' is 'naam simran' or meditation / rememberence on name or existence of Vaheguru 24x7 which however anyone can do whether Sikh or not.Then why be a Sikh? Sikhi makes it core belief with institutions founded by Gurus for a faster way of liberation. However the path can be difficult depending on individual, one should have strong faith in the Guru.