Christianity says that God is triune. But why would the necessary being necessarily have to be triune? You can deduce many attributes of the necessary being but you will never come to conclusion that it must be triune! Plus why specifically 3 persons? Why can’t the necessary being be 2 persons or 4 persons or an infinite amount of persons? Once you put a number on God then he ultimately becomes contingent because he could be otherwise. If Jesus is necessary and the Father is necessary and the Holy Spirit is necessary and they are all different how can you have 3 necessary things that are different. This would render all 3 persons contingent.