Since an all-powerful God
could convince everyone that He exists but
did not do that the logical deduction is that God does not want to do that.
Baha'u'llah wrote that God could convince everyone that He exists of that is what God wanted to do.
“He Who is the Day Spring of Truth is, no doubt, fully capable of rescuing from such remoteness wayward souls and of causing them to draw nigh unto His court and attain His Presence.
“If God had pleased He had surely made all men one people.” His purpose, however, is to enable the pure in spirit and the detached in heart to ascend, by virtue of their own innate powers, unto the shores of the Most Great Ocean, that thereby they who seek the Beauty of the All-Glorious may be distinguished and separated from the wayward and perverse. Thus hath it been ordained by the all-glorious and resplendent Pen…”
Gleanings From the Writings of Bahá’u’lláh, p. 71
In the context of the passage above, If God had pleased He had surely made all men one people means that God could have made all people believers, if God had wanted to make all people into believers. The passage goes on to say
why God didn’t want to make everyone into believers... In short, God wants us to make an effort and become believers by our own efforts (by virtue of their own innate powers).