“Knowing, brethren beloued, your election of God.”
1611 King James Version (KJV)
1:4 Knowing your election - Which is through faith, by these plain proofs.
1Th 1:4 Knowing . . . your election of God. That you are of the elect, the "chosen nation" (Ps 33:12 1Pe 2:9). All Christians were the elect, and the expression is another way of saying, "Knowing that you have become Christians".