"So why doesn't God just make it clear to every one what is the one true church and be done with it?"
I will take a crack at this, but by no means should it be considered magisterial...
I will briefly dismiss the obviously false and man-made religions, most of which do not claim to have any exclusive path of salvation. First, all the pagan religions... Who worship creation rather than the Creator. Or worship idols, made of their own hands.
Secondly I will dismiss the religion of Muhammad, a pedophile and worldly man, whose religion is based in lust and plunder.
Third, I will dismiss the religion of today's pharisaical rabbis (Jewish religion), as the Temple was destroyed, as prophesized by Jesus Christ. Sacrifice at the temple was the essential element of the Israelite religion, a precursor to the sacrifice of Calvary. There's no reason for the precursor, now that the crucifixion and Resurrection occurred 2,000 years ago. As they reject Christ, and their Temple was destroyed, they reformulated their religion, such that today it is a man-made affair. They refuse to accept that Jesus expanded his flock to all of mankind, no longer just for the Israelites.
So that brings us to the Christian religion, the Church. Jesus was born of a virgin, performed many miracles, was tortured, crucified and buried. He then rose from the dead. Although there is much credible testimony regarding these events, acceptance of it ultimately comes down to Faith. Having fulfilled the prophecies of the Old testament confirms his unique mission and identity.
God's ways are not our ways. Jesus told Pilate that His kingdom is not of this world. He told the doubting Thomas to examine his wounds and believe... Yet blessed are those who have not seen, and yet believe. So in the mystery of God's order, He desires people to have faith in Him.
The following passages illustrate in some way that the ways of God are not necessarily the ways of men. At His first coming, he did not come as a conqueror like many of the judeans were looking for. He was born in a stable, he escaped death at the hands of Herod, the son of a humble Carpenter.
GOSPEL Matt. 13:24-30
At that time, Jesus spoke this parable to them, saying: "The kingdom of heaven is likened to a man that sowed good seed in his field. But while men were asleep, his enemy came and oversowed cockle among the wheat and went his way. And when the blade was sprung up, and had brought forth fruit, then appeared also the cockle. And the servants of the good man of the house coming said to him. 'Sir, didst thou not sow good seed in thy field? Whence then hath it cockle?' And he said to them: 'An enemy hath done this.' And the servants said to him: 'Wilt thou that we go and gather it up?' And he said: 'No, lest perhaps gathering up the cockle, you root up the wheat also together with it. Suffer both to grow until the harvest, and in the time of the harvest I will say to the reapers: 'Gather up first the cockle, and bind it into bundles to burn, but the wheat gather ye into my barn.' "
GOSPEL Matt. 13:31-35
AT THAT TIME, Jesus spoke this parable unto them, saying: "The kingdom of heaven is like to a grain of mustard seed, which a man took and sowed in his field. Which is the least indeed of all seeds; but when it is grown up, it is greater than all herbs, and becometh a tree, so that the birds of the air come, and dwell in the branches thereof."
Another parable he spoke to them: "The kingdom of heaven is like to leaven, which a woman took and hid in three measures of meal, until the whole was leavened."All these things Jesus spoke in parables to the multitudes: and without parables he did not speak to them. That it might be fulfilled which was spoken by the prophet, saying: "I will open my mouth in parables, I will utter things hidden from the foundation of the world."
Further to discerning which is the true Christian religion... In case you are drawn to protestantism... I refer you to the assembled tracts by Saint Francis de Sales, under the title "The Catholic Controversy." St Francis de sales, through this writing, brought back 70,000 to the unity of the Catholic Church, in the area near Geneva.
https://www.catholicwaypublishing.com/s ... -15-books/
Briefly, part of his argument is that the Protestant so-called reformers have no authority, they were sent by no one, they were usurpers. There were no prophecies which foretold their actions and self-designated mission. They have no jurisdiction to do what they did. They have no miracles to confirm what they taught. St Francis is brutal in his directness against the so-called reformers. The ridicule he dishes out is even humorous at points.
Even among the Protestant sects, which claim that theirs is the true religion? Do Baptists claim that their religion is true, to the exclusion of the Presbyterians? Does the Missouri synod claim it is the true church, to the exclusion of the ELCA?
Do the teachings of the Protestant sects blow with the winds of the world? For example, did Protestants universally reject artificial birth control up until the first part of the 20th century? How many of the sects reject it today? What principle permits the dropping of this prohibition against onanism?
Were the denominations, such as the Anglican religion (England), founded for spiritual purposes? Or was it founded so Henry VIII could divorce his wife and take another, contradicting the words of Jesus? Henry was awarded the title "defender of the faith," by the Pope in Rome, for his written attack on the Lutheran heresy, before he claimed to be head of the Church in England...which found support among certain classes for the purposes of plundering the monasteries of the British isles. Previously, the monastic lands supported the lower classes. (see "A history of the Protestant Reformation in England and Ireland") Did Luther's revolt in northern Germany also find partisan favor with those who lusted after the wealth of the Church? Opportunists.
Contrary to the Protestant sects, the Catholic church has miracles from heaven. The miracle of the Sun at Fatima, acknowledged by the secular and anti-catholic media of the day; Eucharistic miracles where the consecrated host visibly changes into flesh and blood... Which holds up under scientific examination. The Catholic Church also has prophecy, such as from Quito Ecuador (our Lady of good success).