I put this entry in general section as I think it is not apt to in my theologization group. True, God has instructed all matter of life and godliness to us by His divine power through the knowledge of Him...(2 Peter 1:3), which only the Scripture sets. But this extends to art, politics, etc. all of which no doubt must be biblical, though limitation in terminologies calls for proper categorization.
On issue of breastfeeding during worship service, my quick response is no. In a church worship, one can expect good, respectful fellowship with each other, but one certainly cannot expect all to be Christians much less pious. A sense of 1 Corinthians 8 is applicable here.
To take on the proponents of this, I would inquire where is their submissiveness.
From the invisible church's perspective, human body and nature are certain nothing to be ashamed of. But when in a Sunday service, it is a time for public fellowship, unless both parties do not mind fellowshipping while breastfeeding. As I would have no problem myself, to give a smile to a mother breastfeeding in the back corner of the pews. Though should I have the authority, I would opt differently, and that perhaps there be a special room for breastfeeding while attending worship service.