Was the council of Nicea, that was headed by Constatine, the worst thing to happen to the world?

Answer 1

No,
Nicea was one of the Best Things to happen to the world since it proclaimed Jesus Christ as God,consubstantial with the Father.

I thank God for all the Ecumenical Councils of His Church.

Nicea and all the Councils have been directed by God the Holy Spirit.

Answer 2

Probably not the worst thing. In fact, from a political standpoint, it might have kept the Empire from fragmenting over the then-recent "acceptance" of Christianity by Constantine.

But, what it really did was reinstall the superiority of the "schools" over the concept of the Spirit. Scholars became the determiners of doctrine. To join the "church", one had to study and serve a sort of internship for several years before being allowed to be baptized. Church leaders where not ordained "by the laying on of the hands, as was Aaron", but rather studied in the schools (early versions of the university) and thereby became "qualified" as one who could read and articulate the interpretation of scripture for the masses (rhetoric was a core subject).

Worse things could have happened. By uniting the various Christian sects doctrinally, the scriptures were codified and standardized ("canonized") and were able to be copied and preserved for later generations. It was religion by committee. And, a thousand years later, people had had enough of that and the reformation of the church began.

Answer 3

Not even close.

The worst thing that ever happened to the world was Original Sin.

Original sin is the sin by which the first human beings disobeyed the commandment of God, choosing to follow their own will rather than God's will.

As a consequence they lost the grace of original holiness, and became subject to the law of death; sin became universally present in the world.

Besides the personal sin of Adam and Eve, original sin describes the fallen state of human nature which affects every person born into the world, and from which Christ, the "new Adam," came to redeem us.

For more information, see the Catechism of the Catholic Church, sections 396 and following: http://www.usccb.org/catechism/text/pt1sect2chpt1art1p7.htm#396

With love in Christ.