Assurance of salvation
Before the creation of the universe God thought of me. He fixed his gaze on me and chose me for himself. He did not choose me because I was already in Christ of my own doing, but that I might be in Christ. He did not choose me because he saw me as a believer, but so that I might become a believer. He did not choose me because I chose him, but so that I might choose him. He did not choose me because I was holy or good but so that I might become holy and good.
Everything I am and all I hope to be is rooted in God's freely choosing me. My faith, my hope, my work are not the ground of electing grace but only its effect. And so there is no ground for boasting except in God. And in the face of fear and loss of assurance and all my own defect, I speak this word of trust: "Who shall bring any charge against the Lord's elect!" (Romans 8:33).
John Piper, "God Has Chosen Us in Him Before the Foundation of the Earth"