Asking why we should care if God exists is a bit like asking why we should care if water or air exists. The first reason we should care if God exists is because He is our Creator. If the triune God of the Bible does not exist, then neither would we exist (1 Corinthians 8:6). We live only because He has given us life (John 1:3–4). God is both the creator and sustainer of all living things, including you and me (Genesis 1:1–2; Colossians 1:16). It is in God that "we live and move and have our being" (Acts 17:28). It is God who upholds and sustains our existence as well as the existence of the entire cosmos (Hebrews 1:3). The knowledge of God reveals the personal and powerful cause behind our creation and continued existence. However, God did not give a bare or minimal existence, but has blessed us greatly in what He has made us (Psalm 8:5–6; 139:14) and what He has provided for us (James 1:17; 1 Timothy 6:17). Furthermore, knowing our Creator provides us with the purpose for our existence, which is to know, love, enjoy, serve, and glorify God forever (1 Corinthians 8:3; 10:31; Matthew 22:37–40; Psalm 16:11).
Why should we care if God exists?
A second reason we should care if God exists is because God is our Judge (Psalm 7:11–13; 50:6; 58:11; Ecclesiastes 12:14; Acts 10:42; Romans 2:3; 2 Timothy 4:1; Revelation 20:11–15). God created man and woman with the ability to freely obey or disobey Him. God promised deadly punishment would follow disobedience (Genesis 2:16–17). Because of Adam and Eve's disobedience, we have fallen under the curse of sin and death (Genesis 2:17; James 1:15). We have inherited a rebellious nature and we act in accordance with it (Romans 5:12). We are born in a state of separation from and hostility towards our Creator (Genesis 3:23–24; Psalm 51:5; Colossians 1:21; Ephesians 2:1–3). Therefore, we are all guilty before God and are deserving of His just wrath (Romans 1:18; 3:23; Colossians 3:5–7; Ephesians 5:6). God's judgment is just since He has given us clear proof of His existence as well as conscience and law through which we know right from wrong (i.e. what pleases Him from what displeases Him) (Romans 1:19–21; 2:12–16).
Last and certainly not least, we should care whether God exists because salvation can only be found in Him (Psalm 3:8). Despite our willful rebellion against His sovereign rule, God has loved us and given His Son, Jesus Christ, to die for our sin (Romans 5:8). Indeed, there is no other name given among men whereby we must be saved (Acts 4:12). Through believing in and receiving Jesus Christ as our Lord and Savior we are forgiven of our sin because He suffered the wrath of God in our stead (Isaiah 53:5–6; Romans 4:25). By faith in Christ we receive the righteousness of Christ and therefore we are restored to a right standing and relationship with God (Romans 3:21–26; 4:5). In short, we who were enemies of God are reconciled to God through faith in Christ and His shed blood (Romans 5:10; Colossians 1:20). We are redeemed, justified, adopted, sanctified, and will be glorified by God our Savior (Galatians 3:13; Romans 5:1; 8:30; 1 Corinthians 6:11). The greatest part of salvation is that we will dwell forever with God on the new earth (heaven) in glorified bodies (Revelation 21:3; 2 Peter 3:13; Philippians 3:20–21). There will be no more suffering, pain or tears (Revelation 21:4). There will be love, joy, and peace in the eternal presence of God. However, those who reject the salvation of God offered through faith in Christ will suffer God's just wrath and eternal condemnation (John 3:18).
There are many more reasons why we should care whether God exists. However, the fact that God is Creator, Judge, and Savior ought to be sufficient reason for anyone and everyone to care about His existence, and to examine the truths about Him which have been revealed to us in the Bible (John 20:30–31).
Does God exist?
Can the existence of God be proven?
Why does God require faith?
How can a person find God? What does finding God mean?
Does God love me?
Truth about God