I've always applied Romans 12:1-2 to individual Christians. But look at it.
"I appeal to you therefore, brothers (plural), by the mercies of God, to present your bodies (plural) as a living sacrifice (singular), holy and acceptable to God, which is your spiritual worship. Do not be conformed to this world, but be transformed by the renewal of your mind ..."
Paul envisioned all the individuals in the church community offering up their bodies corporately to God as one living sacrifice. It's no coincidence that he continues on in the following verses (3-13) to show us what it looks like to be a body that humbly serves one another in love. From this text and others we see that gospel transformation is something God wants for us to experience together. We change together as we remember God's mercy, live humbly and are committed to community. On Sunday I preached from Romans 12:1-13 on this topic. I pray it encourages you.