#Quite easily, if it was in His nature.

If He wanted to, God could easily create a circumstance within which everybody would have to believe. After all, He *is* omnipotent, omniscient, and infinitely powerful. **However, the key word is "want."**  

I am not sure if this is true for Judaism and Islam, but in Christianity, **God's nature is immutable.** This is a side effect of His eternal ("all of time at the same time") nature; were he to change<sup>[1]</sup>, it would cause a universe-ending grandfather paradox. As a result He cannot do things like sinning, since it is contrary to His nature. Think about it this way: it is within my power to troll everybody on Worldbuilding.SE, but it is against my nature; therefore, it might as well be impossible.

Another thing that Christianity holds true about God is that He values human free will. In fact, it is the whole reason why He created us. As the great theologian Francis Schaeffer put it, "to love Him on a personal, not a machine, level.” (*Genesis in Space and Time*, page 60). This value for our free will goes so far that He even lets people continue in sin, as doing so is what they choose. **As a result of this, Christians have concluded that it is in God's nature to always respect human free will.**

**Since God's nature is immutable, and it is in His nature to allow people free will, He cannot force people to acknowledge His existence.**

Regardless of whether or not He can do such a thing, I think it is worth mentioning that most Christians who see lots of people from all religions and walks of life starting to say that a being/person is God will immediately go into "the sky is falling!!!" mode, assuming that said being/person is the Antichrist. Provided, of course, that the Antichrist hasn't already come...