Telling what Jesus has done for us is wonderful. Certain Protestants -- especially the evangelicals -- have made it into an art form, and woe to you if you are not up to it.
To some Protestants, a testimony must be readily available. Which means you might be called upon at any time, in any meeting, to tell what Jesus has done for you. On Youtube, you can find a multitude of such: "From Prison to Preacher!," "Gangland to God!"
All of which is wonderful. If -- big if -- you have such a testimony. But woe to you if you were "born in a Christian home" (to use the stock phrase) and have no such testimony. In such cases, one must find whatever tiny aspects of rebellion and sin were manifest in childhood, and out of these fashion the debauchery from which you were then saved.
(Franklin Graham -- son of Billy and Ruth, and a man doing some very admirable work -- is nevertheless one such bad example, in his book Rebel With a Cause).
Even Protestants who give up their faith still cling to the testimony motif. Bart Ehrman, who no longer considers himself a Christian, nevertheless continues the testimony theme in his book God's Problem in which the first several pages are devoted to giving a testimony and then what we might term an anti-testimony.
But famous or not, all Protestants like testimonies. Without a good one, there will be whispered doubts about your salvation. Conversely, the more lurid and debauched your life-before-Jesus, the higher your ranking will go amongst the saved.