Certainly, being in Christ, I stop acting according to the flesh, and my body, my soul are only one with the Spirit.

As for the past way of life, get rid of the old man, who is vitiated according to deceptive desires,
23 and renew yourself in the spirit of your mind,
24 and put on the new man, created according to God in the justice and holiness of truth.
25 Therefore, rejecting the lie, let each one speak truth with his neighbor; because we are members of each other (Ephesians 4: 23-25)

And this new being needs to talk about the Lord, glorify him with his Word, done action in everything I do and say.

but sanctify God the Lord in your hearts, and always be prepared to present defense with meekness and reverence to all who demand reason for the hope that is in you (1 Peter 3:15).
Why I DO NOT speak anymore.

Because it is not you who speak, but the Spirit of your Father who speaks in you (Matthew 10:20)

Certainly, I CANNOT shut up, because now I live for Christ.