“The strength of a nation lies in the homes of its people” was credited by realty groups to Abraham Lincoln (1809-1865) in 1983 and later years; the Lincoln attribution was debunked in 2003. A similar saying has been cited in print since at least 1911 (but not attributed to Lincoln):
 
“Philosopher and poet are alike in the verdict that the safety and perpetuity of any nation lies in the homes of its people.”
 
“The strength of a nation lies in the home of its people” was used by the American Lumber Congress in 1919 as part of an “own your own home” campaign.
 
         
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8 May 1911, Kalispell (MT) Journal, “The Home Circle,” pg. 5, col. 1:
Philosopher and poet are alike in the verdict that the safety and perpetuity of any nation lies in the homes of its people.
 
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21 April 1919, Lumber, “Resolution Adopted by American Lumber Congress,” pg. 31, col. 2:
Strength of a Nation
Whereas, The strength of a nation does not lie in its navies, its harbors, its army or navy, its waterways, railways, its manufacturing industries, or not alone upon its natural developed or undeveloped resources, but inasmuch as the strength of a nation lies in the HOMES of its people, as the greatest strength and bulwark — therefore be it
 
Resolved, That this American Lumber Congress assembled do hereby endorse and commend the Department of Labor of the Federal Government in their effort and co-operation and influence in the movement of “OWN YOUR OWN HOME” campaign.
 
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Rebuilding Family Life in the Post-War World:
An enquiry with recommendations
By Sir James Marchant
London: Odhams Press
1948
Pg. 48:
The most valuable asset of a nation is the health and physique of its people and, as King George V truly said, “the glory of a nation lies in the homes of its people.”
       
12 April 1953, Fort Pierce (FL) News-Tribune, pg. 13, col. 1 ad:
“The Security of a Nation lies in the Homes of Its People”
First Federal Savings & Loan Association of Fort Pierce
 
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17 February 1983, Peterborough (NH) Transcript, “Private Property Week set,” pg. 22, col. 5:
“The strength of a nation lies in the homes of its people,” Abraham Lincoln.
 
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1 December 2003, Star-News (Wilmington, NC), “Things Lincoln never said,” pg. 7A, cols. 1-2:
Here are some of the phrases frequently—and wrongly—attributed to Abraham Lincolm, according to Illinois state historian Thomas Schwartz:
(...)
“THE STRENGTH OF the nation lies in the homes of its people.”
Widely quoted on homebuilders’ and real estate Web sites, the closest utterance resembling it is in an August 1928 speech by President Hoover: “The foundation of American life rests upon the home and the family.”