My pastor was saying that the presence of God in our midst is the essential element of the character of our congregation. He said that worship was the means to invite God's presence with us because He is seeking worshippers who do so in spirit and in truth.
This reminded me of the story of two close friends. One man was trusting and simple while his friend loved to play pranks on him. Once, the prankster called to fool his friend into believing that the roof of his house was on fire. But, the friend said, "You can't fool me this time, John, I recognize your voice."
It's like that for the genuine Christian. Once a person has the Holy Spirit living within his or her spirit, the Holy Spirit gives impressions to direct the believer. The believer learns over time the difference between his own conscience, the thoughts put there by outside influences, and the believer's best friend, the Holy Spirit. We know Him spirit to spirit, our eternal spirit to the Holy Spirit.
When we worship in spirit and in truth, we are reaching out our spirit to touch the presence of the Holy Spirit. The Holy Spirit responds with a sense of love, of forgiveness, of healing, of wisdom for a certain situation, or some other spiritual gift, if only the sweet savor of His embrace.
It is in our sweet surrender to His love for us that we acknowledge that His gracious love has won our heart at last. We set ourselves aside for Him and we set Him aside for ourselves. But how can we who are so small set God aside for ourselves?
Remember the marriage vows that a husband gives a wife and that a wife returns to her husband? They each choose to accept the other as the one and only one for them. They "forsake all others and keep themselves" only to each other. Likewise, we see all of the other beliefs, but we choose Christ and set Him aside unto ourselves as the only recipient of our faith and faithfulness.
We realize that our love with Christ will provide us with the love essential for our spouses, families, and others. Because we offer worship as a genuine expression of self-sacrifice to our Savior, we also sense His loving grace towards us.
It is now that we begin to understand Colossians 1:26 "Christ in us, the hope of glory". That is to say, Christ in us by the presence of the Holy Spirit is the source of the expression of God's presence and character in our lives.
Now we can say, "I know Whom I have believed..." in worship.