is Christ” is to be filled with faith, hope, and love. Hope in the eternal life of Christ. Faith that fully trusts in his eternal life. And love that flows from his life of love in you.
“To live is Christ” means we are filled with love as a state of being. Love is. And love is in us. Why? Because Christ is in us. Without love we are nothing because without Christ we are nothing. But in Christ we are everything because his love has made us everything.