There are many reasons for joining another church. The JW religion is basically unfulfilling as a way of life, it requires complete dedication to the rules of the GB, but gives very little back. Meetings, study and field service is constantly emphasized, to the exclusion of all else in life. They constantly preach doom and gloom, the idea that God will soon destroy all mankind, sparing only JWs, and probably not all of them. It has a rigid mindset of struck adherence to burdensome, man made rules, many not even found in the bible. The meetings are tedious and field service is futile. Personal expression is discouraged, there is often mean gossip and fault finding in the congregation. Joy is completely lacking.
But there are benefits from belonging to a faith based community. I believe we all naturally have a sense of spirituality. It doesn't necessarily have to be expressed as a particular religion, or even belief in God. But belonging to a good church does have benefits, it encourages spiritual thinking by regular meetings, it offers a sense of community, it encourages charitable giving, it encourages personal expressions of faith, and it offers support in times of trouble.
I respect those who do not feel this need, or who do not believe in God, that is understandable, I felt the same, for many years after I left. But now I find myself open to the idea of joining a church and I have been attending one for the last few months. I haven't joined yet, it's too early to say if this is for me, but I am enjoying it so far, and see many benefits to joining.
