Pickthall: (We take our) colour from Allah, and who is better than Allah at colouring. We are His worshippers.
The following excerpt is taken from “Anwar ul Bayan” vol 1 pg. 141:
Allah Has Colored us
Asabun Nuzul has reported from Sayyidina Abdullah ibn Abbas (Radihullahnhu) that the Christians used to baptise their on the seventh day after birth using some coloured water. They considered this as a form of purification for their children and also regarded it as a substitute for circumcision. Only after this rite did they regard the child as a proper Christian.
Allah refers to this practice in the above verse and makes it clear that only the colouring of Belief (Iman) and good deeds given by Allah is what should be desired. No other colouring and baptism can be better than Allah’s colouring of a person with Belief (Iman). Therefore, the Believers are exhorted to proclaim, ‘Allah has coloured us. Who can colour better than Allah? And we are His worshippers.”
This announcement is a proclamation of steadfastness as Muslims. They will never forsake this divine colouring because none other can colour a person as Allah can. The baptism practised nowadays is done with clean water with the same intention of purification. Although physical purity may be attained by it, spiritual cleanliness is not.
The following excerpt is taken from “The Study Quran” under the commentary of the above verse:
“Some commentators mention Christian baptism and understand this verse to assert the superiority of Islam, as the true baptism of God, over the Christian rite (Th). Other interpretations include ṣibghah as “purification” and also as the wont of God, God’s “wont” being His unchanging actions in relation to the world (see 17:77; 33:38; 33:62; 35:33; 40:85; 48:23). For others the ṣibghah may denote God’s religion (dīn; R). These interpretations can be seen as complementary, as God’s wont, religion, creed, and purification have overlapping significance, and all are brought out by the range of meaning in the term ṣibghah in the sense of an original dye or coloration by God in the fabric of existence.”
Madani, Muhammad. Anwar ul Bayan. (vol. 1 p. 141). http://www.islamicweblibrary.com/wp-content/uploads/2020/04/Tafsir-Anwarul-Bayan-01.pdf
Nasr, Hossein (2015). Study Quran. http://www.islamicweblibrary.com/wp-content/uploads/2020/04/TheStudyQuran.pdf