My fiance is a COGIC (Church of God In Christ) minister and continually says I am not as "spiritual" as I should be although he admits that I am "growing." I am not sure I understand this concept and what it is that I am lacking and what I am seeking.
I'm not sure what he thinks you are lacking and what you should be seeking, other than that you should be seeking to know Jesus, the Messiah. He could answer that question better than I.
Perhaps, though, he should pay attention to Jesus, who said, "Judge not, that you be not judged, for with whatever judgement you judge, you will be judged; and with whatever standard you use, the same standard will be used with you." (Matthew 7:1-2) I don't know what standard he is using to determine whether or not you are spiritual enough. I know he can't read your heart, and thus use the only valid standard. "The LORD seeth not as man seeth; for man looketh on the outward appearance, but the LORD looketh on the heart." (1 Samuel 16:7) Only God can judge your heart, whether or not you are spiritual or not.
Some Pentecostals I know do judge with a false standard. They say that you must not be very spiritual if you don't exhibit the gifts of the Holy Spirit, most particularly "speaking in tongues." This is a false standard for three reasons. First, there are many who will argue from scripture that those gifts are no longer available to men; that they ended shortly after the end of the first century. This is based on Acts 8, where only the apostles had the ability to impart the gifts. Even those on whom they had laid their hands could not pass them on, so the gifts must have ended shortly after the last apostle died. Second, Paul considered "speaking in tongues," which in the Bible meant speaking in known human languages that the speaker had not learned in the normal way, the least important of all the gifts (1 Corinthians 14:5, 19). Many Pentecostals judge spirituality by whether a person has this least important gift. Additionally, they define speaking in tongues as speaking some unknown and often unknowable language, while in the Bible it always meant an identifiable human language. Third, even Paul said that those who had the gifts of the Holy Spirit (as distinct from the gift of the Holy Spirit) were sometimes unspiritual. In 1 Corinthians 14 he accused them of causing confusion in the church, in opposition to what God wanted.
If someone says you are not as spiritual as you should be, that also implies that the one saying that thinks he is as spiritual as he should be. None of us are perfect. Even Paul said he had to work at his own spirituality (1 Corinthians 9:27). Anyone who judges the spirituality of another should follow Jesus' advice. "And why beholdest thou the mote that is in thy brother's eye, but considerest not the beam that is in thine own eye? Or how wilt thou say to thy brother, Let me pull out the mote out of thine eye; and, behold, a beam is in thine own eye? Thou hypocrite, first cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother's eye." (Matthew 7:3-5)
My fiance says that because I only go to church when he goes, I only read the Bible when doing research, and I don't pray (don't know how he came to that conclusion) that my commitment to Christ is weak. How do you determine someone else's commitment to Christ?
You don't determine someone else's commitment to Christ; that is God's job. "Judge not, that ye be not judged. For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again. And why beholdest thou the mote that is in thy brother's eye, but considerest not the beam that is in thine own eye? Or how wilt thou say to thy brother, Let me pull out the mote out of thine eye; and, behold, a beam is in thine own eye? Thou hypocrite, first cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother's eye." (Matthew 7:1-5) It is enough of a problem to worry about oneself and one's own spirituality.
Paul talked about the weaker brother, but said that even if another is, or appears, weaker in the faith we are supposed to accept them just as we accept anyone else. "Him that is weak in the faith receive ye, but not to doubtful disputations." (Romans 14:1) He goes on to say that our job is not to judge such a person, but to teach them. "Brothers, even if a person is caught in a sin, you who are spiritual are to restore such a one in a spirit of gentleness, lest you also be tempted" to sin by judging. (Galatians 6:1)
Within the past few days I answered another question on "Pentecostal spirituality." The problem I have with what I understand as "Pentecostal spirituality," which may be a misunderstanding on my part (but probably not, from what you are saying) is that it encourages one to judge others. Particularly, it forces one to judge others based on faulty standards. We are to teach, not judge. And when another's understanding is better than ours, we should recognize that and learn from them. That is one reason I so enjoy answering these questions; I sometimes learn from the questioner, and am happy to admit it.