Genuine relationships share at a deep level.  They are not a forum for people to get as much out of each other as they can - that sort of behaviour breeds distrust and separation.  City life is full of superficiality and Paul's plea to the believers in Rome was counter cultural (Romans 12:1-2).  Within the church especially, it matters that people share together. Those who rejoice need others to rejoice with them about the Lord's goodness. And those who grieve need compassionate empathetic souls to share their grief.  

The Bible word for ‘sharing’ is also used for ‘fellowship’, ‘giving’, ‘partnership’, ‘communion’, ‘distribution’, ‘intimacy’ and ‘communication’.  That intimacy of ‘fellowship’ stems from the Oneness of the Father, Son and Holy Spirit.  The way the three Persons of the Godhead relate together is the basis for all good human relationships, family (Ephesians 3:14-15) and church.

However, it is sacrificially difficult to lay aside our own ideas and emotions, to share the gladness or sadness of others. It is a challenge to our own plans, which may need to be rearranged to spend whatever time is necessary.  It is a challenge to our pride; there is usually nothing we can contribute, except to be alongside, understand and be a real brother or sister.  The only thing we can do is to encourage our friend to share it with our Heavenly Father as well.

'Living in harmony' really means 'having the same attitude of heart'. Philippians 2:2-3 says, "...then make my joy complete by being like-minded, having the same love, being one in spirit and of one mind. Do nothing out of selfish ambition or vain conceit. Rather, in humility value others above yourselves..."  When the joy of others attracts only a reluctant response, and the sadness of others encourages us to give advice - it shows that our sinful nature is desperate to make ourselves big at the expense of others.  It was not like that with Jesus: 2 Corinthians 8:9 says, "For you know the grace of our Lord Jesus Christ, that though he was rich, yet for your sake he became poor, so that you through his poverty might become rich.." Let us decide to have Christ-like responses today.