Old beliefs die hard even when demonstrably false.E.O. Wilson
Events in 1854 led to an anti-slavery north forming the Republican Party. Originally, Abraham Lincoln held back from the Republican Party as he wanted the Whig Party to be the party of anti-slavery. It wasn’t until 1856 that Lincoln established the Illinois Republican Party . Republicans today sometimes claim pride in being in the party that Lincoln helped establish. The problem with this is that the Republican Party today has only the name in common with the party of Lincoln.
It would be simple to just conclude that the Republican Party of today is the party of Lincoln. But that would be wrong. The more complex answer has to dive into history and see what events led to the reversal of platforms, and the complete transformation of both parties. In the time of Lincoln and for a long time after, “the Democrats were supported by southern social conservatives in rural areas who did not want slavery to end, while the Northern Republicans were embraced by northern progressive liberals who strived to end slavery once and for all.” 
In 1912, during a progressive era which both parties embrace, Teddy Roosevelt left the Republican party and formed the Progressive Party or Bull Moose Party. This began an imbalance in the progressiveness of the parties, as the Republicans became more conservative. Between 1933 and 1939, FDR ushered in the New Deal which consisted of a lot of social welfare programs.
In 1948, “Truman, a Democratic Southerner, introduced a pro-civil rights platform at the party’s 1948 convention” , which led to a faction called the “Dixiecrats” and the first time when the south was no longer dominantly Democrat. When LBJ, another Democratic Southerner, signed the Civil Rights Act of 1964, the south began to switch to their once hated Republican Party in droves.
Given the complex nature of the platform drift over history, is it actually fair to say that the Republican Party of today is the party of Lincoln? The Republican Party of today is the party with the strong toe-hold in the south, which throughout history has never been the party of Lincoln.
 2005, Doris Kearns Goodwin, Team of Rivals
 June 24, 2019, Democrats and Republicans Platform Switch Throughout US History, https://www.bleumag.com/2019/06/24/democrats-and-republicans-platform-switch-throughout-us-history/
 April 10, 2019, How the ‘Party of Lincoln’ Won Over the Once Democratic South, https://www.history.com/news/how-the-party-of-lincoln-won-over-the-once-democratic-south