The moment we begin to rest our peace on anything in ourselves, we lose it, and this is why so many saints have not settled peace.
Nothing can be lasting that is not built on God alone.
How can you have settled peace? Only by having it in God's own way, by not resting on anything, even the Spirit's work within yourselves, but on what Christ has done entirely without you. Then you will know peace, conscious unworthiness, but yet peace. In Christ alone, God finds that in which He can rest; and so it is with His saints. The more you see of the extent and nature of the evil that is within as well as that without and around, the more you will find that what Jesus is and did, is the only ground at all on which you can rest.