Non-believers are without excuse

Non-believers Are Without Excuse.

Why Christians are without excuse. 

The apostle Paul promises his flock that God will straighten out the points of Christianity.

If they grasp anything in the wrong way, God will intervene to make it clear‑‑
Philippians 3:10 I want to know Christ--yes, to know the power of his resurrection and participation in his sufferings, becoming like him in his death, 11 and so, somehow, attaining to the resurrection from the dead.
12 Not that I have already obtained all this, or have already arrived at my goal, but I press on to take hold of that for which Christ Jesus took hold of me. 13 Brothers and sisters, I do not consider myself yet to have taken hold of it. But one thing I do: Forgetting what is behind and straining toward what is ahead,
14 I press on toward the goal to win the prize for which God has called me heavenward in Christ Jesus.
15 All of us, then, who are mature should take such a view of things. And if on some point you think differently, that too God will make clear to you. 16 Only let us live up to what we have already attained. 

But, on the radio, the Bible Answer Man says nobody can comprehend the nature of the trinity.
They can apprehend it (hear about it) but not comprehend it.
It sounds as if the matter hasn't been made clear.
Paul's promise isn't being kept.

Yet Paul insists that God has made himself plain to non-believers, so that they are without excuse.

Romans 1:20 [S]ince the creation of the world God’s invisible qualities--his eternal power and divine nature--have been clearly seen, being understood from what has been made, so that people are without excuse. 

Judging by the many sects of Christianity, the churches hold differing views of Christianity.
Catholics believe one thing, Mormons another, Methodists and Baptists, too.
They should be a single church, moving in the same direction.
But churches express different versions of Christianity.
Paul's promise makes them without excuse.
And what's more, God hasn't put them on the right road.

Moreover, Jesus sought unity, praying for everyone to be of one accord--

John 17:20 My prayer is not for them [the disciples] alone. I pray also for those who will believe in me through their message, 21 that all of them may be one, Father, just as you are in me and I am in you. May they also be in us so that the world may believe that you have sent me.

22 I have given them the glory that you gave me, that they may be one as we are one: 23 I in them and you in me. May they be brought to complete unity to let the world know that you sent me and have loved them even as you have loved me. 

Jesus' prayer assures they'll be one church body.

But there's not one church, despite the promise of Paul and the prayer of Jesus. 

Therefore, saying non-believers are without excuse is like the pot calling the kettle black.