The Power of the Gospel
Jesus Christ strengthens us by means of the Gospel. Paul says that in his closing Doxology in Romans. In First Corinthians he says that he was called by God to be a messenger of the Gospel, which he summarizes succinctly as "Christ crucified." He says that this message is "the power of God and the wisdom of God."
The Gospel strengthens. The Gospel is wisdom and power. On a similar note, Laura at A Practice in Belief explains her blog's name this way:
I've re-titled this blog "A Practice in Belief" to reflect how I've come to see the absolute necessity and centrality of the continual preaching of the Gospel even within the body of Christ. Generally we see the Gospel as the thing that we present to nonbelievers, trusting that by means of that message the Spirit will effectually call those whom God has elected for salvation. But the fact is, we humans are sorrowfully forgetful. Luther said that the "default mode" of our heart is self-salvation - living as if we must add our own good works to Christ's in order to be made righteous in the sight of God. Following the example of Paul, who repeatedly tells us that this is not the case, we in the Church have to keep preaching the gospel to each other. Our once-for-all belief is kept for us in heaven (1 Peter 1:3-5), but at the same time, we have to exercise that faith - we have to practice living according to that belief.This is the point that God seems to be bringing home to me again and again. It's all about the Gospel, son. The Gospel of Christ crucified is the one infinitely applicable message. It is the source of your strength in all things. Whatever your situation, search out the proper application of the Gospel message to that situation. You will never graduate to higher things or deeper truths than this message of Christ crucified.