Jim, if you are saved in Jesus, you are no longer a sinner, but a Christian saved by His grace into a new creation in Christ. They who truly believe in Jesus' virgin birth, death and resurrection are no longer a sinner and do not continue in our sins by sinning willfully. If we should slip and sin, Jesus is our Advocate between God and man. When satan accuses, Jesus tells the Father that we are His, so therefore no longer does the devil have a stronghold on us!
Pray about the situation of portraying Lord Jesus in the play and ask for guidance to whether you should play the part or not! Listen to His still small voice in your heart and He will lead you in what you should do. If there is no peace for you, then you shouldn't, but after prayer and seeking God, Who can bring peace, then go ahead, as you could play the part of Jesus and show others His wonderful love of loving the world so much that He gave His own life that we might be saved to not be in the Lake of Fire, which is the second death, but never ever dying!
God Bless and let the world see Jesus' light reflected from within you as a Child of God!
Betty