Obviously, that logic can not be true as it is not in harmony with the rest of the New Testament. Clearly, the Word of God tells us that not all will be saved. Jesus said, "Enter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat: because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it" (Matt. 7:13-14).
I believe the most important question is, how does one get to be considered "in Adam" and "in Christ?" Most if not all theologians believe one is "in Adam" simply by being born into the human race. However, that presents a problem. Our verses say "all!" In the Romans passage, even the context fails to explain how "all" could be lost, and "all" will be saved. Two verses use the word "many" in describing those in Adam and those in Christ (v. 15, 19). Verse fifteen speaks of many dying, when we all know, death is universal (apart from Enoch, Elijah, and those caught up in the Rapture). The same verse compares that with salvation being a gift unto many (the argument requires "many" here to also be universal, with the exception of Judas Iscariot, the Antichrist, and the False Prophet of Revelation). Verse nineteen says, "For as by one man's disobedience many were made sinners, so by the obedience of one shall many be made righteous." Here again, the structure of the argument requires that the "many" made sinners be the same as the "many" made righteous. if by "many," Paul meant "all" when describing the sinners, then he must be saying "all" will be saved.
I believe the answer lies in how we get "in" Adam and "in" Christ. The Word is clear that one is baptized (Spirit baptism - Gal. 3:27; Eph. 4:5) into Christ when he places faith in Him. I would like to challenge the belief that man is born "in Adam," by suggesting we become "in Adam" when we act like Adam. Just as one becomes born again in Christ by trusting in God, one becomes spiritually dead when he ceases to trust in God. That is, when Adam sinned, he no longer believed God. He chose to believe Satan and he died spiritually. When we choose to trust in God's Son instead of the world, the flesh, and the devil, we become "in Christ."
That solves the "all" problem concerning "all" being saved. It also solves the "many" problem in regards to the "many" in Adam. Now all I have to figure out is Psalm 51:5! That may take a while!
If it takes a choice to be saved, why does it not take a choice to be lost?