Why are there infidels when He sent apostles to all people?

If God had willed, everyone would have been a believer but then where is the test of the knowledge, sense of understanding, feeling, knowledge and free will? This life is a test for the hereafter and therefore this has not happened among other reasons known only to God. There are infidels because they rejected the apostles sent to them. The pagan Arabs appointed daughters to God whereas others appointed sons to God.