Jesus made it very easy for us to know who to love and serve: Everyone. Our approval is not required. People do not need to be perfect, pulled together, or washed to be loved. We are all broken, that’s why we need a Savior.
Judgement is not our job. Our job is to love people regardless of who they want to marry, what they eat, or the color of their skin. Yes, they are probably living outside the parameters that God set up, but love them anyway.
Change comes when people feel accepted for who they are. Once they feel valued, they will be open to hearing what you have to share. But don’t share with a pointed finger. Share with arms of love. Be a friend. Help where you can. Pray for them.
The kingdom of God is about people loving people, and not just other people in the kingdom. The Good Samaritan (Luke 10:25-37) was despised by the Jews, yet he was compassionate and generous. Imagine a kingdom where we all lived like that.
If you know you have issues with other people, give them to God. Confess your judgmental attitude to God and ask Him to fill you with His love. Be the heart of God to others and you will release blessing on yourself.