With so many churches, religions and denominations, how do I know how to truly be saved so I can spend eternity with God?
Believe in what?
Rom 10:17 So then faith cometh by hearing, and hearing by the word of God.
The first step is understanding who God is and why we need to be saved
God is the creator of all things, the designer of the universe, planet Earth and all living things, including human beings - Genesis 1
Man disobeyed God and sinned - Genesis 3
God spared us from total destruction thanks to men like Noah and Abraham - Genesis 6 and Genesis 12-25, James 2:23
God manifested Himself in the form of a human being with the birth of Jesus Christ - 1 Tim 3:16, John 1:14, Isaiah 9:6, Matt 1:23
God paid the price for our sin by dying for us, in our place - Romans 5:8
All have sinned, every single one of us - Romans 3:23, Romans 3:10, 1 John 1:8
We are "saved" from our sin and the penalty of that sin, and given the opportunity to live forever with Jesus - Romans 6:22
Once we understand and believe that, then we should repent (sorrowfully reconsider ourself and turn to Jesus)
God is a Holy God who cannot look upon wickedness - Hab 1:13
He is gracious and merciful and wants everyone to come to Him in repentance - 2 Peter 3:9
We love Him because He first loved us - 1 John 4:19
No greater love is found than in he who lays down his life for his friends - John 15:13
We begin to see life in a different way - Romans 6:4
We confess our faith and obey the Gospel by being Born Again
Confess our sin to God - 1 John 1:9
Confess our faith to men - Romans 10:9-10, Acts 8:37
Obey the Gospel (death, burial and resurrection of our spirit) - 1 Peter 4:17, 2 Thess 1:8
Repent and be baptized in the name of Jesus Christ, and receive the promised gift of the Holy Spirit - Acts 2:38, Romans 6:3-7, Acts 3:19, Acts 17:30, Acts 26:20, Mark 16:16
Follow Jesus in obedience and remain faithful to Him
Pick up our cross and follow Jesus - Matt 10:38, Matt 16:24
Cease from sin - 2 Tim 2:19, Psalms 97:10, Romans 6:15, Hebrews 10:26, Galatians 2:17, Hebrews 12:14
Do works meet for repentance - Acts 26:20, James 1:27
In short, hearing and understanding the Gospel is knowing that God came to the earth in Jesus Christ and died for you, so you don't have to.
If you believe that, then tell Him so and turn to Him in obedience.
Let go of your pride and humble yourself before the Mighty God, who loves you enough to die for you.
The Lord is loving and merciful and there is no sin too dark for Him to forgive.
Give it to Him and turn to Him with faith and meekness of spirit, and He will lift you up.
Jesus loves you and He just wants you to love Him back.
Please do not allow anyone to deceive you with words like, "You don't have to do that", or "The Bible doesn't say that".
If the Bible says it in one place, but doesn't in another, that doesn't mean that the Bible doesn't say it.
We have to take the whole Bible as truth and let it all work together to make a complete truth. We can't take pieces out and ignore other places.
Please see - The Bible Doesn't Say That - for more information on this.