One such difficult text is 1 Cor 15:21-22
1 Cor 15:21 For since by man came death, by Man also came the resurrection of the dead. 22 For as in Adam all die, even so in Christ all shall be made alive."
If I were a universalist, and I assure you I am not, this would be one of my proof texts. Sadly this is also used to proof text the doctrine of original sin, and I only say sadly because of the second part of verse 22 which on face value seems to teach universalism. From these two verses, it should be clear that Adam and Christ are both representatives of mankind. The difficulty is we're not applying the "all" which applies to Adam, to the "all" which applies to Christ. IOW, in Adam all of mankind fell, in Christ all of the elect shall be "made alive", the meaning of "all" is used in two different senses, or is it? How can Christ be a representative of all mankind, if the atonement be not sufficient for all?