If your Esther Steckel was the one baptized in 1810 at Egypt Reformed Church, Egypt, Whitehall Township, now Lehigh County, Pa. (daughter of Peter and Elizabeth Steckel), that places your Thomas Gangwer in that vicinity. There was a Thomas Gangewehr in the 1840 census in North Whitehall Township, just over the border from Whitehall Township, who could be your Thomas. He is listed as aged between 20 and 30, with 2 males under 5, 1 female under 5, and 1 female between 20 and 30 living in his household.
Also in the 1840 census for North Whitehall Township is Jacob Gangewehr, with household as follows:
1 male 40-60
2 males 20-30
1 male 10-15
2 females 15-20
1 female 10-15
This could be the father of your Thomas. If I were you, I would check for Thomas's baptism in the records of the Neffs Union Church (a.k.a. Schlosser's Church), Neffs, North Whitehall Township. The building was originally shared by two congregations--hence "Union"--one Lutheran and one Reformed (now United Church of Christ, or UCC). Both congregations are still in existence. This church, which was founded about 1750, would have been the only church in North Whitehall Township at that time.
Neffs Union UCC contact info may be found at http://www.unionucc.org/
. Click on "About Us" and then "History" for a history of the church. Some early records are online at http://www.rootsweb.com/~palehigh/Schlosserschurch.html
. (I did not see the Gangwer family in this database, which means they may have been Lutheran.)
Neffs Union Lutheran Church may be found at http://www.unionlutheranchurch.org/
Note: In 1810, Lehigh County was still a part of Northampton County. It split off in 1812. To further complicate matters: Whitehall Township was created in 1753 (when it was still part of Northampton County), then divided in 1810 into North and South Whitehall. In 1867 a new Whitehall Township was portioned from North and South Whitehall, so that today there are three townships with "Whitehall" in their name, all in Lehigh County: Whitehall, North Whitehall, and South Whitehall.
The Steckel family was a very old and established one in Lehigh County, and much is written about them. Esther Steckel's baptism record may be found at ftp://ftp.rootsweb.com/pub/usgenweb/pa/lehigh/church/egyp000...
Hope this info helps. Good luck!