Before you participate in the Lord's Supper you need to take a little time to examine your heart. You do not need to partake if you are dealing with hard feelings toward another, doubting your faith, or are not a Christian. You are welcome to come to the Lord's Table, but you are not invited to eat until you have accepted the invitation and prepared yourself to follow Jesus. That means you do not partake in an unworthy manner. It is an act of worship and keeping yourself holy.
If you partake in the Lord's Supper in an unworthy manner it will affect your spiritual life, but it could also affect your health. Some people become weak, sick, or die. Judge yourself according to God's Word to walk in confidence. Learn to be self-disciplined and judge yourself, so that there is no room for others to judge you and you can face God without doubt.
Now is the time to self-examine. Now is the time you can fix erroneous thinking, face doubt, and get your salvation worked out. Now is the time to start building your relationship with God. If you wait, then you are at risk of eternal separation and no more second chances. You are not prepared for the Lord's table is you are not a Christian. Following Jesus in faith is what makes you worthy.
The first step in self-examination is to question your faith. Is it real, inherited, a title, or something you rejected? Do you see Jesus in your life? Do you have any doubts in your faith? These will answer the questions if you are a true Christian or not. If you are not a true Christian, then now is the time to come to Jesus. If you are, then now is where you identify where you still need to work out your faith.
You have the Holy Spirit living within you if you are a true Christian. He testifies about your spirit. You obey Him because you love Him. It is your obedience that reveals your salvation. He is what makes you worthy to partake in the Lord's supper. There is no other way to approach God, but through Jesus and the Holy Spirit.
Matthew 22:11-13, Romans 8:15-17, 2 Corinthians 11:27-33, 13:5-6, Hebrews 11:1-2, James 3:1-2, 1 Peter 1:10-11, 1 John 2:3-6, 3:23-24, 4:13-16