there is criteria so that we can identify Gods people, its laid out in the bible:
Criteria 1 - Love
John13:34 I am giving YOU a new commandment, that YOU love one another; just as I have loved YOU, that YOU also love one another. 35 By this all will know that YOU are my disciples, if YOU have love among yourselves.
Criteria 2 - Gods word must be upheld and taught as truth and put into practice
John 8:31 If YOU remain in my word, YOU are really my disciples
John 17;17 Sanctify them by means of the truth; your word is truth.
Criteria 3 - Separateness from the world including political neutrality.
John 17:14 '...the world has hated them, because they are no part of the world, just as I am no part of the world"
Criteria 4 - Make known Gods name.
John 17:6 I have made your name manifest...'
John 17:26 And I have made your name known to them and will make it known
Criteria 5 - Do Gods will....the work that Jesus did was to preach the message of the kingdom of God...that is Gods will.
Matthew 7:21 Not everyone saying to me, Lord, Lord, will enter into the kingdom of the heavens, but the one doing the will of my Father who is in the heavens will
Matthew 28:19 Go therefore and make disciples of people of all the nations, baptizing them in the name of the Father and of the Son and of the holy spirit, 20 teaching them to observe all the things I have commanded YOU. And, look! I am with YOU all the days until the conclusion of the system of things.
Criteria 6 - Peace and unity must exist among them and no national barriers or cultural barriers should divide them as they should all be one in unity and love.
John 14:27 I leave YOU peace, I give YOU my peace.
2 Thessalonians 3:16 Now may the Lord of peace himself give YOU peace constantly in every way. The Lord be with all of YOU.
some denominations may have one or two of these criteria, but not all of them. Some may only focus their efforts on helping the poor with material goods, some may only focus on building churches and baptizing, some may only focus on have social gatherings as a way to show love to each other... but a denomination needs to exhibit each of the above criteria.