'Belong' in the Bible

And if you belong to Christ [if you are in Him], then you are Abraham’s descendants, and [spiritual] heirs according to [God’s] promise.

And those who belong to Christ Jesus have crucified the sinful nature together with its passions and appetites.

So then, while we [as individual believers] have the opportunity, let us do good to all people [not only being helpful, but also doing that which promotes their spiritual well-being], and especially [be a blessing] to those of the household of faith (born-again believers).