This world is full of millions of beliefs. How do we know which one is true? 4+4 = 8, correct? How can 4+4 = 10? That is what many people believe. How can all roads lead to God? There can only be one road. If all beliefs contradict one another, how can all of them be true? The answer is, they cannot.

There can only be one truth. 4+4 can only equal 8, not 10.

The word contradict is key. Yes, all religions teach some forms of morality. However, just because there is some good doesn't mean the entire belief system is the truth.  For example, let's compare Jesus Christ (C) and Muhammad (M). How do their teachings differ?

Here are just a few of of their teachings:
(M) stoned women for adultery (C) said, Let he who is without sin cast the first stone
(M) said, I have been commanded to fight against people till they testify that there is no god but Allah, and that Muhammad is the messenger of Allah, (C) said, He who lives by the sword will die by the sword
(M) permitted stealing from unbelievers (C) said, thou shalt not steal
(M) beheaded 800 Jewish men and boys (C) killed no one
(M) said, Jihad in the way of Allah elevates one's position in Paradise by a hundred fold (C) said, Blessed are the peacemakers, for they will be called Sons of God
(M) Fight everyone in the way of Allah and kill those who disbelieve in Allah (C) said, Love your neighbor and pray for those who persecute you.

As you can see with just a few examples, though, Islam and Christianity are both religions, the teachers contradict each other on many subjects.

How can two differing world views lead their followers to the same god?

It is man's responsibility to find the truth. God will guide the sincere seeker to Himself. 

Matthew 7:7-8 King James Version (KJV)
7 Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you:
8 For every one that asketh receiveth; and he that seeketh findeth; and to him that knocketh it shall be opened.