""For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God." 1 Corinthians 1:18
The Bible is clear about this. If you don't believe the preaching of the cross, what is your guarantee that you are on the right track? Have you believed or contrived another way to God? There isn't one and there will never be one. Many American unbelievers have made up their own version of the gospel of Jesus Christ and there are many from other countries that have varying philosophies that include Jesus as a good man or do not include Jesus at all. But the preaching and believing of the cross is the power of God. There is no spiritual power under the authority of God, given to those who have not accepted His Son. ("He that believeth on Him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God." John 3:18)
Note: I know that this concept really irks the wishy-washy Christian; you know, the ones that like it when everything goes their way; they go to church but have high expectations that it will start and finish according to a prescribed, very short and unassuming timeline and that the pastor will reserve himself/herself to speak only of a very narrow and fully denominational, un-offensive message. As a matter of fact this group is insulted if they are told anything that they don't already know. They don't like new light peering in to their home-grown version of Christianity. They are all-inclusive and consider Christianity as just one of ,many paths to God. This group doesn't need to read the Bible, because the Bible has become archaic; good for denomination building only, but never to enhance a personal and vibrant relationship with Jesus.
What really gets me is that many believers today, Christians that have already have been saved, have a propensity to be casual, indifferent and even apathetic concerning this issue. Many modern Christians seem to have no real roots that cause them to look back and recognize where they were and how gracious God has been in setting them free. There is a tendency in our society to accept any philosophy as valid as long as someone before them believed it, like in the case of Buddhism, and Islam. There is no doubt that we should and must be respectful with those of other faiths and wholly understanding of their position, but never confirming the validity of their beliefs or standing in agreement with them concerning their beliefs, as if these alternate philosophies were sister religions to Christianity, or that there must be some validity to their belief in another god, simply because they believe it.
'Recognition of' and 'respect for' everyone of another faith is the right thing to do. But acknowledgement of the premise that "All paths lead to God" is not the right thing to do.
I've heard the argument that "it just isn't any of our business what others believe. I'll believe what I want to and you believe what you want to." That's fine, but in no way and at no time should a Christian be in agreement or act like they are in agreement with those who deny Jesus.
If you aren't sure about the cross and you are not sure if Jesus died for your sins and if you aren't sure that Jesus is the only way to God, so be it. But don't call yourself a Christian. Anybody can believe any philosophy, but the power of God rests in the hands of those who have placed their faith and allegiance to Jesus.