Grumbling and complaining is contagious and only destroys. It does not build up others, but it only destroys.
Galatians 5:14,15 “The entire law is summed up in a single command: “Love your neighbor as yourself.” If you keep on biting and devouring each other, watch out or you will be destroyed by each other.
Phil 2:14, 15 says…
14Do everything without complaining or arguing, 15so that you may become blameless and pure, children of God without fault in a crooked and depraved generation, in which you shine like stars in the universe.
When we grumble and complain against each other, we tarnish the God’s people and we tarnish the name of Christ.
Phil 2:1-8 reads…
1If you have any encouragement from being united with Christ, if any comfort from his love, if any fellowship with the Spirit, if any tenderness and compassion, 2then make my joy complete by being like-minded, having the same love, being one in spirit and purpose. 3Do nothing out of selfish ambition or vain conceit, but in humility consider others better than yourselves. 4Each of you should look not only to your own interests, but also to the interests of others.
5Your attitude should be the same as that of Christ Jesus:
6Who, being in very nature God,
did not consider equality with God something to be grasped,
7but made himself nothing,
taking the very nature of a servant,
being made in human likeness.
8And being found in appearance as a man,
he humbled himself
and became obedient to death—
even death on a cross!
Jesus, the Creator and Sustainer of the universe gave himself up for you and I to the point of death. Putting ourselves first and arguing our opinions is not Christ-like. If you find yourself grumbling and complaining against others, talk to God about it and ask Him for patience and understanding as well as courage. If you see something wrong, you may be required to speak up proactively and assertively rather than slander your brother behind their back. If you’ve chosen to lovingly confront with humility, then how they respond to your cautions or concerns is between them and God.