You need to find a church that preaches the gospel of Jesus Christ and not a "social gospel". That at age 18 you are desiring to go back to church may be the Lord's urging in your life. In theory, you do not need to attend church in order to know the truth and get right with the Lord.
Here is the fundamental message of salvation through Jesus:
1. We are sinners: Romans 3:23 (NKJV, New King James Version), “for all have sinned and come short of the glory of God”
2. Sin and not believing in Jesus brings eternal condemnation: Romans 6:23 (NKJV), “For the wages of sin is death, but the gift of God is eternal life through Christ Jesus our Lord.” John 3:18 (NKJV), “He who believes in him is not condemned; but he who does not believe is condemned already because he has not believed in the name of the only begotten Son of God.”
3. God loves us and has provided an escape from eternal punishment: John 3:16 (NKJV), “For God so loved the world that he gave his only begotten Son, that whoever believes in him shall not perish but have everlasting life.”
4. Jesus is the only way: John 14:6 (NKJV), Jesus answered, "I am the way, the truth and the life. No one comes to the Father except through me.”
5. Salvation is by the grace of God through our faith: Ephesians 2:8,9 (NKJV), “For by grace are you saved, through faith - and this is not of yourselves, it is the gift of God - not of works lest anyone should boast.”
6. Salvation is the result of confessing that Jesus is Lord and that He was resurrected from the dead: Romans 10:9,10 (NKJV), “If you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved. For with the heart one believes unto righteousness, and with the mouth confession is made unto salvation.”
7. Jesus is waiting at the door to enter your life: Revelation 3:20 (NKJV), “Behold, I stand at the door and knock. If anyone hears My voice and opens the door, I will come in to him and dine with him, and he with Me.”
8. Don't procrastinate, seek the Lord while He is near: Isaiah 55:6 (NKJV), “Seek the LORD while he may be found; call upon him while he is near.”
If you have the 8 points above correct, you are on the right path, the straight way and will enter through the narrow gate: Matthew 7:13. Here is a suggested prayer to help you acknowledge your decision to accept and believe in Jesus: “Dear Lord Jesus, I know that I am a sinner, and I ask for your forgiveness. I believe you died for my sins and rose from the dead. I trust and follow you as my Lord and Savior. Guide my life and help me to do your will. In your name, Amen.” And, as promised in 1 Corinthians 2:9 (NKJV), you will not be disappointed: “But as it is written: Eye has not seen, nor ear heard, nor have entered into the heart of man the things which God has prepared for those that love him.”
If you know Jesus as your Savior and Lord, then the next step is to find a church in which you will grow in God's Word as well as have fellowship with other believers.
One way you can find a church that will support your growth as a believer is to go to the church's website and look at their statement of faith. You should be able to (mostly) find the same scriptures as above in that statement of faith.