Assurance May Be Shaken

The Question that I want to pose to you this morning is this – How is it, then, that when Christ’s work is so sure; His having accomplishing everything necessary for our redemption, and the Father and He have given the Spirit to indwell the believer, and apply the benefits of salvation most surely to each one who believes; and then there is also a definite witness with the believer’s spirit that they are a child of God; how is it, then, that a Christian’s assurance can be shaken, diminished, and intermitted in various ways?