1 I appeal to you therefore, brothers, by the mercies of God, to present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship. 2 Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect.
Many of us make an incredible amount of decisions in our daily lives. As we go along we make up our minds and change them, and some of us change them over and over again. But what does it mean to renew our minds in the context of offering ourselves up in worshipping God? There are two different competing truths in the life of the Christian. There is the universal truth; this is what is objectively true, which is given to us by God through His Word. The second is the things which we feel to be true. In other words, these are the ideas that are driven by emotions or on some desire to define ourselves. The renewing of our minds as believers means turning from what we desire to be true or we feel to be true, and instead clinging to what God says to be true.
In the Christian life, we are called to renew our minds. This means fundamentally changing how we think. For instance, it is not uncommon for people to live in paralyzing guilt for decades. This is despite what God says He thinks when He looks at us. He tells us that there is “…therefore now no condemnation for those who are in Christ Jesus.” (Romans 8:1). So to resolve our guilt, we must give up what we think God sees when He looks at us for what He says is actually true. Another example could be found in how we identify ourselves. We may have our own ideas on how we define our sexuality, marriage, or singleness, but as believers we must lay those aside in favor for what God says is true. We are to come to the cross laying down all those things which we often call our own, and by which we look at and identify ourselves, and pick up a new identity as Paul writes in 2 Corinthians.
Since, then, you have been raised with Christ, set your hearts on things above, where Christ is seated at the right hand of God. Set your minds on things above, not on earthly things. For you died, and your life is now hidden with Christ in God. -Colossians 3:1-3
The renewing of our minds is an act of worship, because it is us laying down everything that we think about ourselves and saying that we believe God for everything that He says instead. This is what made King David a "man after God's heart". It was clearly not because He was perfect, in fact, he was arrogant, selfish, and guilt of some pretty terrible crimes. The one thing that he got right was that he knew and believed God rather than trusting and believing in his own feelings. The Psalms are ripe with passages written by David proclaiming his hopeless feelings and circumstances, but he always ends with coming back to a realization that He can trust in the promises of God more than his feelings or his perception of his circumstances. This transformation is not easy or self-evident as Paul says; it comes through testing and discernment. The goal though is that we might present ourselves as a sacrifice ready to give every thought, feeling, desire, and emotion to God, and instead of hanging on to these, cling to His promises and our new identity in Christ. This is our reasonable act of worship. Isn't it about time we change our minds?