1. A witness is what we are.

He told them, “This is what is written: The Messiah will suffer and rise from the dead on the third day, and repentance for the forgiveness of sins will be preached in his name to all nations, beginning at Jerusalem. You are witnesses of these things. I am going to send you what my Father has promised; but stay in the city until you have been clothed with power from on high.” Luke 24:46-49

“But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth.” Acts 1:8

God has raised this Jesus to life, and we are all witnesses of it. Acts 2:32

2. A testimony is what we share.

And this gospel of the kingdom will be preached in the whole world as a testimony to all nations, and then the end will come. Matthew 24:14

But you, man of God, flee from all this, and pursue righteousness, godliness, faith, love, endurance and gentleness. Fight the good fight of the faith. Take hold of the eternal life to which you were called when you made your good confession in the presence of many witnesses. In the sight of God, who gives life to everything, and of Christ Jesus, who while testifying before Pontius Pilate made the good confession, I charge you to keep this command without spot or blame until the appearing of our Lord Jesus Christ, 1 Timothy 6:11-14

So then, King Agrippa, I was not disobedient to the vision from heaven. First to those in Damascus, then to those in Jerusalem and in all Judea, and then to the Gentiles, I preached that they should repent and turn to God and demonstrate their repentance by their deeds. Acts 26:19-20

3. We support the testimony of the church:

A. By living a Godly life,

Whatever happens, conduct yourselves in a manner worthy of the gospel of Christ. Then, whether I come and see you or only hear about you in my absence, I will know that you stand firm in the one Spirit, striving together as one for the faith of the gospel Philippians 1:27

B. By attending faithfully,

And let us consider how we may spur one another on toward love and good deeds, not giving up meeting together, as some are in the habit of doing, but encouraging one another—and all the more as you see the Day approaching. Hebrews 10:24-25

C. By giving regularly.

A tithe of everything from the land, whether grain from the soil or fruit from the trees, belongs to the LORD; it is holy to the LORD. Leviticus 27:30

On the first day of every week, each one of you should set aside a sum of money in keeping with your income, saving it up, so that when I come no collections will have to be made. 1 Corinthians 16:2