"That your rejoicing may be more abundant in Jesus Christ for me by my coming to you again." (Philippians 1: 26)
We are in Christ, and Christ is in us:
"And ye are Christ's; and Christ is God's." (1 Corinthians 3: 23)
In Christ, we have the promise of consummate victory:
"Nay, in all these things we are more than conquerors through him that loved us." (Romans 8: 37)
"Now thanks be unto God, which always causeth us to triumph in Christ, and maketh manifest the savour of his knowledge by us in every place." (2 Corinthians 2: 14)
When we recognize other members of the Body of Christ as in Christ, then we rejoice and enjoy fellowship with one another:
"But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin." (1 John 1: 7)
Our celebration with others in the Body of Christ is all about the truth which sets us free (John 8: 32), the grace of God for all our sins:
"4I rejoiced greatly that I found of thy children walking in truth, as we have received a commandment from the Father." (2 John 4)
Now, you may have struggled in relationships with some people in your church.
Paul explains why there is conflict in certain churches:
"For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men?" (1 Corinthians 3: 3)
And the law is the strength of sin (1 Corinthians 15: 56), which leads to conflicts among those who rest in His grace, vs. those who wrestle with the law:
"28Now we, brethren, as Isaac was, are the children of promise. 29But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now." (Galatians 4: 28-29)
When we see ourselves in Christ completely, without any assistance from our efforts, and others understand our blessed standing in Christ, then indeed we rejoice!