In writing this thesis, the author tries to examine the effect of the Holy Communio n service on the spiritual growth of the GMAHK Bunsadan Kota Marudu Sabah Cit y of Malaysia congregation based on 1 Corinthians 11:27. This research is based on four indicators: The theological understanding of the word "unworthy" in 1 Corinthians 11:27; how to attend the Lord's Supper to be considered worthy; the impact of the Holy Communion Service on the spirituality of the members of the congregation and the views of the experts on the spiritual growth in the Holy Communion. This research is divided into two main parts, which is theoretical research and field research. From the result of theoretical research, the meaning of the word improper can be found in 1 Corinthians 11:27 where it refers to eating and drinking as the Corinthians did, who ate it not referring to the death of Jesus Christ's sacrifice (without respect), but in a manner like the Israelites made the Passover , which they celebrate as a reminder of their liberation from Egyptian slavery. The one who is deemed worthy to attend the Holy Communion service are those who have been baptized and are following the worship according to the Adventist Church's rule book. There are several benefits of attending the Holy Communion service which are commemorating His sacrifice, being humble, reconciling and developing the Spirit of service. Experts say that this Holy Communion service is very important because it encourages God's people to have an ethical life according to God's word and live a spiritual life. In the field research, the results of the respondents provide information that all statements contained in the questionnaire (P1 - P20) are well understood except for statements P1 - P5 where the respondent gives a hesitant answer. Overcoming this, the writer will give a seminar in connection with the writing of this thesis.