For we all stumble in many ways. If anyone does not stumble in what he says, he is a mature (teleios) man who is also able to control his whole body. (James 3:2)
Stumbling is easy for the Christian and is a common experience for all of us. The teleios is a measurement of the moment of where we are at in our journey. The use of our speech, or what we post on social media is an opportunity to stumble with our expression.
A sign of spiritual maturity is how a Christian speaks; does he or she speak in love with the goal of edification?
If I speak human or angelic languages but do not have love, I am a sounding gong or a clanging cymbal. (1 Cor 13:1)
No foul language is to come from your mouth, but only what is good for building up someone in need, so that it gives grace to those who hear. (Ephesians 4:29)
The whole man or woman is in mind with the statement of control over the whole body. Self-control is a mark of spiritual maturity as seen in the following growth passages:
His divine power has given us everything required for life and godliness through the knowledge of Him who called us by His own glory and goodness. By these He has given us very great and precious promises, so that through them you may share in the divine nature, escaping the corruption that is in the world because of evil desires. For this very reason, make every effort to supplement your faith with goodness, goodness with knowledge, knowledge with self-control, self-control with endurance, endurance with godliness, godliness with brotherly affection, and brotherly affection with love. For if these qualities are yours and are increasing, they will keep you from being useless or unfruitful in the knowledge of our Lord Jesus Christ. (2 Peter 1:3-8)
But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faith, gentleness, self-control. Against such things there is no law. (Galatians 5:22-23)
Do not get discouraged that you have not reached the goal of teleios. Do measure yourself from time to time with the desire to grow in your faith and build godly character. Submit to the work of the Holy Spirit and let God grow you His way. Perfecting the saint is the business of the Lord; allow Him to work in you.