When Christ is made known to our soul by the power of God, we have views of truth in him, of happiness in him, and of deliverance. "As ye have therefore received Christ Jesus the Lord, so walk ye in him." We receive him as the Son of the Father in truth and love; we receive him as suitable to our wants and woes; we receive him as putting away sin by the sacrifice of himself, and endearing himself to our heart in the sweet manifestation of his Person, goodness, and love.
Now as long as Christ and the soul are together, there is no place for error, and no place for evil. He makes the soul tender, the heart upright, the spirit broken and contrite, truth precious, error hateful, and sin loathsome and detestable. And whilst he and the soul are engaged together, error cannot approach nor evil find an entrance, so as to get any standing-ground in the heart. But error is very subtle; it addresses itself to our reasoning powers; and when we lose sight of Christ, then error very easily creeps in; or if not error, some special lust, or something ungodly, seems by degrees to obtain power and influence, and we gradually decline from the strength of faith, the confidence of hope, and the sweet affections of love, and drop, it may be, into a cold, carnal, careless, lifeless state, where we lie open to the invasion of error and the temptations of Satan as an angel of light or an angel of darkness.
But now Jude comes and says, "Keep yourselves in the love of God; and I will tell you, if you will listen to me, how you shall do it. You must build up yourselves on your most holy faith." God has laid a foundation for your faith in his holy word; he has laid Christ as a foundation in your own soul. That is a very strong foundation; it is of God's own laying. It is very solid; it will bear any weight laid upon it. And therefore you must build up yourselves upon that most holy faith if you would have a religion which stands; because if your religion, or any part of your religion, be built upon another foundation, it will not stand. But if you build up yourselves on your most holy faith, then everything you build upon it will stand, because it rests upon the foundation, and is in harmony with it.