Right, and the FV repeatedly say that the difference between the elect and nonelect in the covenant community is in fact the latter--the elect are doers of the Word, while the nonelect are hearers only. And 1 Cor. 10:1-6 says that those who fell away partook somehow in what the sacraments represented, i.e., Christ Himself.
One who experiences "forgiveness" is more than a hearer of the Word, he is a partaker of what the Word promises to the children of God. Wilkins states that forgiveness can be lost. You know this, which is evident from the fact that in your previous post you tried to include forgiveness in kingdom blessings to the non elect.
Concerning 1 Cor. 10, yes, they partook of Christ SACRAMENTALLY. But sacramental participation is only effectual with respect to the elect. Hence sacramental participation in Christ does not necessarily mean that they were REALLY in Christ. Only on the basis of the FV understanding of "sacramental efficacy" could one leap from SACRAMENTAL to REAL participation in Christ. Such a view destroys the sacramental union between the sign and the thing signified by confusing them.