A quotation of Dr. Singh on 'Nature and Nature of Things' as below may help answer your question,
"The most scientific, universal and truly spiritual doctrine bestowed on the entire humanity with immense love and compassion and without any bias, discrimination, criticism and hatred towards any body is 'Sikh Religion'.
Only the blessed and truly wise with true humility and love for truth, true spirituality and service to the creation of the Creator really want to know, understand and practice it.
This is the first and foremost spiritual doctrine that recognized and unequivocally established the pious and highly respectable status of women and discrimination.of any kind towards any one.
It is a religion in it self and not an off shoot of any other religion, however some may feel the other way round in there utter ignorance.
It teaches, to be truly human and humane and never to be a hypocrite other wise the doors to true spirituality would never ever open, what to say about the path, journey, destination and The Goal.
It is a journey so simple yet so immense which is only to be cherished and experienced and is beyond any description."
Ik Onkar meaning one supreme lord is a very big teaching in Sikhism. We believe in the teachings of our Ten Gurus. We believe in the Guru Grant Sahib, our holy scripture. Nam Japan which means reading and understanding bani. Kirtan Karo which means to live honestly and earn by ones physical and mental effort while accepting Gods gifts and blessings. Wand Kay Shako which means to share with everyone. Sikhs are expected to develop positive human qualities which leads our souled closer to God and away from evil. Waheguru Ji Ka Khalsa Waheguru Ji Ki Fateh.
Oh and by the way to the person at the top named Yasdani Begum, SIKHS ARE NOT SICK AT ALL!
Three basic fundamentals of Sikh religion are as follows
1. Honest earnings and living (Kirth Kro)
Appears to be very brief but is a wisdom unparalleled and immense in two words, if ones Karma is not honest the doors of true spirituality never open, further as one sows so one has to reap in this world and in the future as well, There is no peace of mind and peace of heart.
2. Share the fruit of of your honest earnings (Vanda Kay sh-KO)
Again concentrated wisdom,
A quotation of Dr. Singh on 'Human Nature and Development' as below gives a simple version,
"Caring is sharing and sharing is caring.
One does not truly care and or share if one is not truly kind and has no feelings of compassion for the sufferings and pain of others. The question of sharing does not arise in the heart of such people but on the contrary they will look forward to rob the others in innumerable ways. Kindness and care towards the Creators Creation generates 'True Love' for thy self, the Creator and Thy Creation. A unique situation of internal and external harmony. Without all these qualities there is no true peace and peace of mind in ones own heart. There may be material gains and materialistic misadventures but the life in reality in one word would always be 'miserable'.
Remember one event leads to an other and so on .................... the true wisdom is only in choosing the right initial step."
3. Meditation/True spirituality (Naam j-PO)
Again the concentrated wisdom in two words, the easiest path towards true spirituality.
However, these steps are in true order. Unless the first one is not truly achieved the second cannot be accomplished and so on.
As per quotation of Dr. Singh "One event leads to an other and so on, the true wisdom is only in choosing the right initial step."
However, Mr. PK Pundit gave an excellent reference, it requires great and true honesty, humility, wisdom and love to understand it.
This spiritual doctrine is a universal message, is the royal road to attain true spirituality and is not limited to the Sikh religion.
The true seekers of true spirituality only need to be true students, honest to the core and don't need and or have to change their religion to get the true wisdom and true spirituality from this most unique and scientific spiritual doctrine.