First, it should be made clear that by "way of life" we mean slavery. Certainly any northern political attempt to halt the spread of slavery into the territories was met with howls of protest and claims that the North hoped to destroy the institution. Events that increased southern fears (as opposed to northern anger) would have to include the publication of Uncle Tom's Cabin in 1852. The book, written in protest against the Fugitive Slave Act of 1850, portrayed slavery as an inhuman and evil institution, quite different from contemporary southern claims that slavery was in fact humane and that slaveholders, unlike northern capitalists, cared for their slaves. The book, much like other abolitionist literature, was banned in the Deep South.
Another event that aroused fears in many slaveholders was John Brown's raid on Harpers Ferry, Virginia (now West Virginia) in October of 1859. While the raid was a spectacular failure, Brown made clear in his trial that he had intended to spark a slave revolt that would spread throughout the slaveholding South. What really increased the fears of Southerners were rumors (eventually proven true) that several prominent Northerners had helped to fund and assist Brown.
A third event, nowhere near as widely known as the other two, was also the publication in 1857 of a book entitled the Impending Crisis of the South by Hinton Rowan Helper. Helper, a white North Carolinian, argued that slavery, because it depressed wages, hindered economic development to the detriment of working-class whites in the South. He called for non-slaveholding whites in the South to overthrow the institution. This anti-slavery document became a very important text for Republicans, who distributed it in the 1860 election. Two years earlier, southern congressmen had refused to seat newly elected members who had given their endorsement to one running of the book.
These events helped convince Southerners that abolition was a growing force in the North and that the Republican Party posed an existential threat to the institution of slavery, including the paternalistic class relations among whites that undergirded it.