Sikhism, science and rationality fit together perfectly. The Sri Guru Granth Sahib Ji talks of other planets and other worlds. There is no denial of scientific truths in Sikhism.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/christianity/8638-why-i-chose-sikh-not-christian.html

God is within all of us. S/he is no distant master.

God is neither male nor female in Sikhism.

In the West, historically, the theological evolution of liberal, spirituality-centered Christians comes to the same conclusions as Guru Nanak (see, for example, Ralph Waldo Emerson, Henry Thoreau)
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=8638

There is no such thing as "fundamentalist Sikhism." The

Five Thieves of Sikhism ask their followers to refrain from habits that apply to everyone. No one is condemned to be a sinner based on who they instrinsically are.

There is no doctrine of "original sin" in Sikhism. Infants are born innocent, not sinners.