The effects that Christ produce in us is such that produce thanksgiving in both us and those around us. When a life is changed from that of a horrible person with the characteristics of that fairy tail character of the Grinch, to that loving person of Christ it produces a grateful heart. Being thankful is a God thing, and it is something that we do towards God such as bringing sacrifices of thanksgiving before him (ps107.22). We all have something to be thankful for of God, he has comforted us when we needed it the most, he has turned dry moments into enriching ones; It’s what God does, and thanksgiving is the product of such (Is51:3).
2 Corinthians 9:11 Being enriched in every thing to all bountifulness, which causeth through us thanksgiving to God.
Paul is working to prepare this church of Corinthians to becoming bountiful givers, for another church; the church of Macedonia, was coming to see their fruit and they needed to be ready. We have been blessed in all things to the point that gratefulness has no other choice but to pour out from us. The scriptures tell us that he shall supply all our needs according to his riches in glory through Christ Jesus (Ph4:19). It also says that God knows all your needs (Lk12:30) and if we seek him he will supply them. When God supplies your needs; whatever they may be say a job, a healing, the effects are to the production of the unspeakable gift through us. When something is unspeakable they are either forbidden to be spoken of, or there is not enough knowledge. But, Christ is the later, we do not have sufficient knowledge to say the things that are his (1Cor2:9). And, that unspeakable gift is Christ in us which produce thanksgiving unto God. In turn, those around us will see your good works and glorify the Father which is in heaven (Mt5:16).