This question gets to the heart of what it means to be in community. Community offers us not only people to be open and honest with, but a place we can call home and understand and serve each other. A non-Christian can and hopefully should be part of your circle of friends! They can also be great listeners, full of grace, and a place of safety. Non-Christians serve and love, and often better than Christians! But, without the element of faith, there will be some lacking.
It is difficult to share our deepest needs and sins with someone who cannot point us to Christ. It is near impossible to learn together how to live out the gospel when one of you doesn’t believe that gospel. As you live life with a non-Christian, pray for them and desire their soul’s salvation to be the highest priority. They will be changed watching you live and love your community. So, yes, a non-Christian can be a part of your community but the depth shared may not be the same. I encourage you to bring them in and then love them to the cross!