I am not so sure you left Christianity, after all, that same ayah speaks of Christ/Messiah and it does not look like it is denying his reality, it is only confused about his full identity and this is very common to (all those who claim to be) Christians.
As about articulating the reality of God, it starts by realizing ‘what God’ is before realizing ‘who God is’. You see, all people are aware of God, otherwise it would be unfair for them to be judged. The difference is the care they take in relating to him. And this affect the articulation of their creeds.
For now, let’s me just proclaim that God is
a unity not
a unit.
Ps. I was watching the stories about Egypt. When one Muslim man was expressing how touched he was by the solidarity among the Muslim and the Christians, he was crying out loud: “in Egypt, the Muslim and the Christian are not two men, they are one”, he repeated it several times. When I looked at him, I say to myself, “This guy is going Christian, he is only not aware of it, I wish that fire could keep on burning”
You see, Faith is mostly a matter of the heart. Just as authentic light shines from a flame where there is energy(power) at the core. In matter of religious Faith, it is not so much the head that sees but the heart.
God bless