Only let your conversation be as it becometh the gospel of Christ.
"The word "conversation" does not merely mean our talk and converse with one another, but the whole course of our life and behaviour in the world. The Greek word signifies the actions and the privileges of citizenship: and thus we are commanded to let our actions, as citizens of the New Jerusalem, be such as becometh the gospel of Christ... We must not forget that the gospel of Christ is holy. It never excuses sin: it pardons it, but only through an atonement. If our life is to resemble the gospel, we must shun, not merely the grosser vices, but everything that would hinder our perfect conformity to Christ. For his sake, for our own sakes, and for the sakes of others, we must strive day by day to let our conversation be more in accordance with his gospel." -- Charles Haddon Spurgeon, Morning and Evening
The word "conversation" finds its etymology in the mid-14th century, "place where one lives or dwells," also "general course of actions or habits, manner of conducting oneself in the world," from the assimilated form of com "with, together" + versare "to turn."
In other words, a conversation is a turning together or a turning with. To converse with another person is to walk along the same path and take the same exits and on ramps. When different paths or on ramps are taken, conversation has ceased.
Galatians 1:13-14
For ye have heard of my conversation in time past in the Jews’ religion, how that beyond measure I persecuted the church of God, and wasted it: And profited in the Jews’ religion above many my equals in mine own nation, being more exceedingly zealous of the traditions of my fathers.
Paul was previously conversant in the Jewish religion. He applied himself entirely to it and pursued it with everything he had. He gave all his heart, soul, mind, and strength to turning with it and on it. He was exceedingly zealous. He was all in and that meant he breathed, moved and had his being in, on and with wherever it turned. He conformed his steps to its imposition.
Our primary conversation is with respect to whether or not we are walking in step with God's revelation. It includes every aspect of life: word, thought, deed, intention and application. It is comprehensive. We will have conversation. Our lives will turn on something and with something. If we are to be Christians, that turning must be entirely on and with Christ.
1 Timothy 4:11-13
These things command and teach. Let no man despise thy youth; but be thou an example of the believers, in word, in conversation, in charity, in spirit, in faith, in purity. Till I come, give attendance to reading, to exhortation, to doctrine.
So if we have been conversing with something or someone other than Christ, we must repent, end that conversation, confess it as sin, and begin conversing with Christ.
Ephesians 5:8
For ye were sometimes darkness, but now are ye light in the Lord: walk as children of light
1 John 1:6-7
If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth: But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.
Our walking speaks to where we are going. Our direction determines our destination. It reveals how we are getting there and with whom we are working to keep up with. Do we turn with Him? Or do we turn to go our own way?
To be a Christian is to keep our steps in keeping with His turnings, following the narrow way and avoiding the broad off ramps.