As a believer, you can know Christ lives in you. When you receive Jesus Christ by faith, you have new life in you, the life of Christ. You can sincerely say, "Christ lives in me, and the life which I now live in the flesh I live by faith of the Son of God, who loved me and gave Himself for me" (Galatians 2:20)
How can you know Christ in you? He lives in you through the Holy Spirit, also known as the Spirit of Christ. His presence is experienced through faith, hope, and love. These are the three abiding gifts of the Holy Spirit. "And now abide faith, hope, love, these three; but the greatest of these is love" (1 Corinthians 13:13).
How does the Spirit of Christ live in you through these three abiding gifts? Faith is in your heart to trust Christ as your living Lord and Savior. Hope is given for you to trust Christ with your future. Most importantly, the love of Christ is in you. The love of Christ enables you to love God and others.
Yes, you can know Christ in you. You know Christ in you by faith. You know Christ in you by hope that the world didn't give you, and the world can't take it away. You have the love of Christ in you, bringing peace and joy. This is the three-fold witness that Christ is in you, through faith, hope, and love.