If an unbeliever invites you to dinner, and you want to go, then go. Eat whatever you are served. Don't cause a problem for someone's conscience by asking where the food came from.
We don't do shameful things that must be kept secret. And we don't try to fool anyone or twist God's message around. God is our witness that we speak only the truth, so others will be sure that we can be trusted.
We know what it means to respect the Lord, and we encourage everyone to turn to him. God himself knows what we are like, and I hope you also know what kind of people we are.