I would not rely on David Barton for accurate information. Barton makes a lot of claims that he doesn't prove. One example is his claim that on December 4, 1800, Congress approved the use of the Capitol building as a church building.
The evidence cited by Barton is: Debates and Proceedings in the Congress of the United States (Washington: Gales and Seaton, 1853), p. 797, Sixth Congress, December 4, 1800.
An examination of the evidence cited by Barton reveals the opposite of his claim. The House declined to even consider "that the Chaplains had proposed, if agreeable to the House, to hold divine services every Sunday in their Chamber."
The Speaker of the House informed the members of the Chaplain's proposal but did not order it assigned to a committee or to lay on the clerk's table for consideration.
No House member moved for it to be assigned to committee or to lay on the table. It went straigt into the trash basket.
It appears that not even one member of the House was interested in a divine services every Sunday in their Chamber.
Follow this link, see the document and make up your own mind if Congress approved the Chaplain's proposal.
http://memory.loc.gov/cgi-bin/ampage?collId=llac&fileName=010/llac010.db&recNum=396
F. Slice
You're confused, they did approve. The rest of that page is about something else.
http://www.loc.gov/exhibits/religion/rel06-2.html
"It is no exaggeration to say that on Sundays in Washington during the administrations of Thomas Jefferson (1801-1809) and of James Madison (1809-1817) the state became the church. Within a year of his inauguration, Jefferson began attending church services in the House of Representatives. Madison followed Jefferson's example, although unlike Jefferson, who rode on horseback to church in the Capitol, Madison came in a coach and four. Worship services in the House--a practice that continued until after the Civil War--were acceptable to Jefferson because they were nondiscriminatory and voluntary. Preachers of every Protestant denomination appeared. (Catholic priests began officiating in 1826.) As early as January 1806 a female evangelist, Dorothy Ripley, delivered a camp meeting-style exhortation in the House to Jefferson, Vice President Aaron Burr, and a "crowded audience." Throughout his administration Jefferson permitted church services in executive branch buildings. The Gospel was also preached in the Supreme Court chambers..."
Accomodation is not establishment, as Jefferson and Madison knew.