When a person obeys the Gospel, that person is added to the church.
As Christians, we have been delivered from the realm of darkness, and we are now in the spiritual realm; we are part of the Kingdom of God.
Col 1:13
13 He has delivered us from the power of darkness and conveyed us into the kingdom of the Son of His love,
Our true citizenship is in Heaven.
Phil 3:20
20 For our citizenship is in heaven, from which we also eagerly wait for the Savior, the Lord Jesus Christ,
The Kingdom of God is righteousness and peace and joy in the Holy Spirit; we have eternal joy and peace.
Romans 14:17
17 for the kingdom of God is not eating and drinking, but righteousness and peace and joy in the Holy Spirit.
We can lose that peace; God can take away the peace He grants us.
Jeremiah 16:5
5 For thus says the Lord: “Do not enter the house of mourning, nor go to lament or bemoan them; for I have taken away My peace from this people,” says the Lord, “lovingkindness and mercies.
BUT, we can maintain eternal joy and peace. Philippians 4 provides the way.
Philippians 4:4-9
4 Rejoice in the Lord always. Again I will say, rejoice!
5 Let your gentleness be known to all men. The Lord is at hand.
6 Be anxious for nothing, but in everything by prayer and supplication, with thanksgiving, let your requests be made known to God; 7 and the peace of God, which surpasses all understanding, will guard your hearts and minds through Christ Jesus.
Meditate on These Things
8 Finally, brethren, whatever things are true, whatever things are noble, whatever things are just, whatever things are pure, whatever things are lovely, whatever things are of good report, if there is any virtue and if there is anything praiseworthy—meditate on these things. 9 The things which you learned and received and heard and saw in me, these do, and the God of peace will be with you.