Sikhs, Sikhism can non-sikhs or those of other faiths, be in one with god as well?

Can I be a great person follow everything about Sikhs and still be one with god? no reincarnation or rebirth?

Seeing as Goddoesn't exist, you will never be "one with him".

It is hard to understand, what you want but yes, you do not need to part of Sikh religion. Guru Granth Sahib contains versions of liberated persons from Hindus and Muslim religions. Their followers who were blessed with true religion were also liberated. Bani of Guru Granth Sahib is for whole humanity. Word Sikh means a disciple. Guru must be perfect, imperfect Guru can sink the boat[other religions claim, they had perfect gurus but there are no writings available from them, Books were completed after their death, in practicality it is not human nature, we forget things even in minutes, Sikh Gurus were blessed to complete Guru Granth Sahib in their life time, they also collected the authentic versions of the true saints of that time] . How we will find a perfect Guru, when when we do not have eyes to judge. Guru Granth Sahib is a criteria. We can pray to God to accept us. A true religious person will not hate person of any other religion or even atheists because he/she looks at his own vices and virtues. It does not mean you do not have to speak Truth, gist of religions is important not the rituals. Gurus dare to speak against all rituals of the religions of that time like:
Idol worship,
Fasting,
Sootak
Patak
Casteism, racism
Man and woman are unequal
Burying is better than burning
Dead will wake up,
Qiamat will come one day
Bowing has no meaning if you miss the time
God lives in Kaaba or Mecca
Offering flowers to deities
Worshiping deities other than one God and the list goes on.
You can learn and liberate yourself by following the teachings of Guru Granth Sahib. You may not be a Sikh in the census column but in fact you will be a true Sikh(disciple).

yes you can, just be a good person, live an honest life, love god with every breath, and treat everyone and everything equally. or you can do what steel boy said, you don't have to be a Sikh to do what guru Grant sahib Jo teaches. but if you feel weird or threatened its understandable and if that's the case then you don't have to. reading UrbainNis for silencing your mind, basically if you read it with sincerity and love you will not have to think with the five thieves in mind. anger, lust, ego, attachment, greed. if you do conquer you mind then you can truly love god.